path: root/libmpdemux/tvi_v4l2.c

/*
**  Video 4 Linux 2 input
**
**  This file is part of MPlayer, see http://mplayerhq.hu/ for info.  
**
**  (c) 2003 Martin Olschewski <olschewski@zpr.uni-koeln.de>
**  (c) 2003 Jindrich Makovicka <makovick@kmlinux.fjfi.cvut.cz>
**  
**  File licensed under the GPL, see http://www.fsf.org/ for more info.
**
**  Some ideas are based on works from
**    Alex Beregszaszi <alex@naxine.org>
**    Gerd Knorr <kraxel@bytesex.org>
**
**  CODE IS UNDER DEVELOPMENT, NO FEATURE REQUESTS PLEASE!
*/

/*

known issues:
- norm setting isn't consistent with tvi_v4l
- the same for volume/bass/treble/balance

*/

#include "config.h"

#if defined(USE_TV) && defined(HAVE_TV_V4L2)

#include <errno.h>
#include <fcntl.h>
#include <pthread.h>
#include <stdio.h>
#include <string.h>
#include <sys/ioctl.h>
#include <sys/mman.h>
#include <sys/time.h>
#include <sys/types.h>
#include <unistd.h>
#ifdef HAVE_SYS_SYSINFO_H
#include <sys/sysinfo.h>
#endif
#include "videodev2.h"
#include "../mp_msg.h"
#include "../libvo/img_format.h"
#include "../libao2/afmt.h"
#include "tv.h"
#include "audio_in.h"

/* information about this file */
static tvi_info_t info = {
    "Video 4 Linux 2 input",
    "v4l2",
    "Martin Olschewski <olschewski@zpr.uni-koeln.de>",
    "first try, more to come ;-)"
};

struct map {
    struct v4l2_buffer buf;
    void   *addr;
    size_t len;
};

#define BUFFER_COUNT 6

/* private data */
typedef struct {
    /* video */
    char			*video_dev;
    int				video_fd;
    int                         mp_format;
    struct v4l2_capability	capability;
    struct v4l2_input           input;
    struct v4l2_format		format;
    struct v4l2_standard	standard;
    struct v4l2_tuner		tuner;
    struct map			*map;
    int				mapcount;
    int				frames;
    long long                   first_frame;
    long long                   curr_frame;
    /* audio video interleaving ;-) */
    volatile int		streamon;
    pthread_t			audio_grabber_thread;
    pthread_mutex_t		skew_mutex;

    /* 2nd level video buffers */
    int                         first;
    int                         immediate_mode;

    int                         video_buffer_size_max;
    volatile int                video_buffer_size_current;
    unsigned char		**video_ringbuffer;
    long long                   *video_timebuffer;
    volatile int		video_head;
    volatile int		video_tail;
    volatile int		video_cnt;
    pthread_t			video_grabber_thread;
    pthread_mutex_t             video_buffer_mutex;

    /* audio */
    char			*audio_dev;
    audio_in_t                  audio_in;

    long long                   audio_start_time;
    int                         audio_buffer_size;
    int                         aud_skew_cnt;
    unsigned char		*audio_ringbuffer;
    long long			*audio_skew_buffer;
    volatile int		audio_head;
    volatile int		audio_tail;
    volatile int		audio_cnt;
    volatile long long          audio_skew;
    volatile double             audio_skew_factor;
    volatile long long          audio_skew_measure_time;
    volatile int                audio_drop;
    volatile int                shutdown;

    double                      audio_secs_per_block;
    long long                   audio_skew_total;
    long			audio_recv_blocks_total;
    long			audio_sent_blocks_total;
} priv_t;

#include "tvi_def.h"

static void *audio_grabber(void *data);
static void *video_grabber(void *data);

/**********************************************************************\

    Only few of the fourccs are the same in v4l2 and mplayer:

    IMGFMT_YVU9 == V4L2_PIX_FMT_YVU410
    IMGFMT_YV12 == V4L2_PIX_FMT_YVU420
    IMGFMT_NV12 == V4L2_PIX_FMT_NV12
    IMGFMT_422P == V4L2_PIX_FMT_YUV422P
    IMGFMT_411P == V4L2_PIX_FMT_YUV411P
    IMGFMT_UYVY == V4L2_PIX_FMT_UYVY
    IMGFMT_Y41P == V4L2_PIX_FMT_Y41P

    This may be an useful translation table for some others:

    IMGFMT_RGB8  == V4L2_PIX_FMT_RGB332
    IMGFMT_RGB15 == V4L2_PIX_FMT_RGB555
    IMGFMT_RGB16 == V4L2_PIX_FMT_RGB565
    IMGFMT_RGB24 == V4L2_PIX_FMT_RGB24
    IMGFMT_RGB32 == V4L2_PIX_FMT_RGB32
    IMGFMT_BGR24 == V4L2_PIX_FMT_BGR24
    IMGFMT_BGR32 == V4L2_PIX_FMT_BGR32
    IMGFMT_Y800  == V4L2_PIX_FMT_GREY
    IMGFMT_IF09  == V4L2_PIX_FMT_YUV410
    IMGFMT_I420  == V4L2_PIX_FMT_YUV420
    IMGFMT_YUY2  == V4L2_PIX_FMT_YUYV

\**********************************************************************/

/*
** Translate a mplayer fourcc to a video4linux2 pixel format.
*/
static int fcc_mp2vl(int fcc)
{
    switch (fcc) {
    case IMGFMT_RGB8:	return V4L2_PIX_FMT_RGB332;
    case IMGFMT_RGB15:	return V4L2_PIX_FMT_RGB555;
    case IMGFMT_RGB16:	return V4L2_PIX_FMT_RGB565;
    case IMGFMT_RGB24:	return V4L2_PIX_FMT_RGB24;
    case IMGFMT_RGB32:	return V4L2_PIX_FMT_RGB32;
    case IMGFMT_BGR24:	return V4L2_PIX_FMT_BGR24;
    case IMGFMT_BGR32:	return V4L2_PIX_FMT_BGR32;
    case IMGFMT_Y800:	return V4L2_PIX_FMT_GREY;
    case IMGFMT_IF09:	return V4L2_PIX_FMT_YUV410;
    case IMGFMT_I420:	return V4L2_PIX_FMT_YUV420;
    case IMGFMT_YUY2:	return V4L2_PIX_FMT_YUYV;
    case IMGFMT_YV12:	return V4L2_PIX_FMT_YUV420;
    }
    return fcc;
}

/*
** Translate a video4linux2 fourcc aka pixel format to mplayer.
*/
static int fcc_vl2mp(int fcc)
{
    switch (fcc) {
    case V4L2_PIX_FMT_RGB332:	return IMGFMT_RGB8;
    case V4L2_PIX_FMT_RGB555:	return IMGFMT_RGB15;
    case V4L2_PIX_FMT_RGB565:	return IMGFMT_RGB16;
    case V4L2_PIX_FMT_RGB24:	return IMGFMT_RGB24;
    case V4L2_PIX_FMT_RGB32:	return IMGFMT_RGB32;
    case V4L2_PIX_FMT_BGR24:	return IMGFMT_BGR24;
    case V4L2_PIX_FMT_BGR32:	return IMGFMT_BGR32;
    case V4L2_PIX_FMT_GREY:		return IMGFMT_Y800;
    case V4L2_PIX_FMT_YUV410:	return IMGFMT_IF09;
    case V4L2_PIX_FMT_YUV420:	return IMGFMT_I420;
    case V4L2_PIX_FMT_YUYV:		return IMGFMT_YUY2;
    }
    return fcc;
}

/*
** Translate a video4linux2 fourcc aka pixel format
** to a human readable string.
*/
static char *pixfmt2name(int pixfmt)
{
    static char unknown[24];

    switch (pixfmt) {
    case V4L2_PIX_FMT_RGB332:	return "RGB332";
    case V4L2_PIX_FMT_RGB555:	return "RGB555";
    case V4L2_PIX_FMT_RGB565:	return "RGB565";
    case V4L2_PIX_FMT_RGB555X:	return "RGB555X";
    case V4L2_PIX_FMT_RGB565X:	return "RGB565X";
    case V4L2_PIX_FMT_BGR24:	return "BGR24";
    case V4L2_PIX_FMT_RGB24:	return "RGB24";
    case V4L2_PIX_FMT_BGR32:	return "BGR32";
    case V4L2_PIX_FMT_RGB32:	return "RGB32";
    case V4L2_PIX_FMT_GREY:		return "GREY";
    case V4L2_PIX_FMT_YVU410:	return "YVU410";
    case V4L2_PIX_FMT_YVU420:	return "YVU420";
    case V4L2_PIX_FMT_YUYV:		return "YUYV";
    case V4L2_PIX_FMT_UYVY:		return "UYVY";
/*	case V4L2_PIX_FMT_YVU422P:	return "YVU422P"; */
/*	case V4L2_PIX_FMT_YVU411P:	return "YVU411P"; */
    case V4L2_PIX_FMT_YUV422P:	return "YUV422P";
    case V4L2_PIX_FMT_YUV411P:	return "YUV411P";
    case V4L2_PIX_FMT_Y41P:		return "Y41P";
    case V4L2_PIX_FMT_NV12:		return "NV12";
    case V4L2_PIX_FMT_NV21:		return "NV21";
    case V4L2_PIX_FMT_YUV410:	return "YUV410";
    case V4L2_PIX_FMT_YUV420:	return "YUV420";
    case V4L2_PIX_FMT_YYUV:		return "YYUV";
    case V4L2_PIX_FMT_HI240:	return "HI240";
    case V4L2_PIX_FMT_WNVA:		return "WNVA";
    }
    sprintf(unknown, "unknown (0x%x)", pixfmt);
    return unknown;
}


/*
** Gives the depth of a video4linux2 fourcc aka pixel format in bits.
*/
static int pixfmt2depth(int pixfmt)
{
    switch (pixfmt) {
    case V4L2_PIX_FMT_RGB332:
	return 8;
    case V4L2_PIX_FMT_RGB555:
    case V4L2_PIX_FMT_RGB565:
    case V4L2_PIX_FMT_RGB555X:
    case V4L2_PIX_FMT_RGB565X:
	return 16;
    case V4L2_PIX_FMT_BGR24:
    case V4L2_PIX_FMT_RGB24:
	return 24;
    case V4L2_PIX_FMT_BGR32:
    case V4L2_PIX_FMT_RGB32:
	return 32;
    case V4L2_PIX_FMT_GREY:
	return 8;
    case V4L2_PIX_FMT_YVU410:
	return 9;
    case V4L2_PIX_FMT_YVU420:
	return 12;
    case V4L2_PIX_FMT_YUYV:
    case V4L2_PIX_FMT_UYVY:
    case V4L2_PIX_FMT_YUV422P:
    case V4L2_PIX_FMT_YUV411P:
	return 16;
    case V4L2_PIX_FMT_Y41P:
    case V4L2_PIX_FMT_NV12:
    case V4L2_PIX_FMT_NV21:
	return 12;
    case V4L2_PIX_FMT_YUV410:
	return 9;
    case V4L2_PIX_FMT_YUV420:
	return 12;
    case V4L2_PIX_FMT_YYUV:
	return 16;
    case V4L2_PIX_FMT_HI240:
	return 8;

    }
    return 0;
}

static int amode2v4l(int amode) 
{
    switch (amode) {
    case 0:
	return V4L2_TUNER_MODE_MONO;
    case 1:
	return V4L2_TUNER_MODE_STEREO;
    case 2:
	return V4L2_TUNER_MODE_LANG1;
    case 3:
	return V4L2_TUNER_MODE_LANG2;
    default:
	return -1;
    }
}


// sets and sanitizes audio buffer/block sizes
static void setup_audio_buffer_sizes(priv_t *priv)
{
    int bytes_per_sample = priv->audio_in.bytes_per_sample;
    double fps = priv->standard.frameperiod.denominator /
	priv->standard.frameperiod.numerator;
    int seconds = priv->video_buffer_size_max/fps;

    if (seconds < 5) seconds = 5;
    if (seconds > 500) seconds = 500;

    // make the audio buffer at least as the video buffer capacity (or 5 seconds) long
    priv->audio_buffer_size = 1 + seconds*priv->audio_in.samplerate
	*priv->audio_in.channels
	*bytes_per_sample/priv->audio_in.blocksize;
    if (priv->audio_buffer_size < 256) priv->audio_buffer_size = 256;

    // make the skew buffer at least 1 second long
    priv->aud_skew_cnt = 1 + 1*priv->audio_in.samplerate
	*priv->audio_in.channels
	*bytes_per_sample/priv->audio_in.blocksize;
    if (priv->aud_skew_cnt < 16) priv->aud_skew_cnt = 16;

    mp_msg(MSGT_TV, MSGL_V, "Audio capture - buffer %d blocks of %d bytes, skew average from %d meas.\n",
	   priv->audio_buffer_size, priv->audio_in.blocksize, priv->aud_skew_cnt);
}

#if 0
/*
** the number of milliseconds elapsed between time0 and time1
*/
static size_t difftv(struct timeval time1, struct timeval time0)
{
    return	(time1.tv_sec  - time0.tv_sec)  * 1000 +
	(time1.tv_usec - time0.tv_usec) / 1000;
}
#endif

/*
** Get current video capture format.
*/
static int getfmt(priv_t *priv)
{
    int i;

    priv->format.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
    if ((i = ioctl(priv->video_fd, VIDIOC_G_FMT, &priv->format)) < 0) {
	mp_msg(MSGT_TV, MSGL_ERR, "%s: ioctl get format failed: %s\n",
	       info.short_name, strerror(errno));
    }
    return i;
}


/*
** Get current video capture standard.
*/
static int getstd(priv_t *priv)
{
    v4l2_std_id id;
    int i=0;

    if (ioctl(priv->video_fd, VIDIOC_G_STD, &id) < 0) {
	mp_msg(MSGT_TV, MSGL_ERR, "%s: ioctl get standard failed: %s\n",
	       info.short_name, strerror(errno));
	return -1;
    }
    do {
	priv->standard.index = i++;
	if (ioctl(priv->video_fd, VIDIOC_ENUMSTD, &priv->standard) < 0) {
	    return -1;
	}
    } while (priv->standard.id != id);
    return 0;
}

/***********************************************************************\
 *									*
 *									*
 *	Interface to mplayer						*
 *									*
 *									*
\***********************************************************************/

static int set_mute(priv_t *priv, int value) 
{
    struct v4l2_control control;
    control.id = V4L2_CID_AUDIO_MUTE;
    control.value = value;
    if (ioctl(priv->video_fd, VIDIOC_S_CTRL, &control) < 0) {
	mp_msg(MSGT_TV,MSGL_ERR,"%s: ioctl set mute failed: %s\n",
	       info.short_name, strerror(errno));
	return 0;
    }
    return 1;
}

/*
** Mplayer uses values from -100 up to 100 for controls.
** Here they are scaled to what the tv card needs and applied.
*/
static int set_control(priv_t *priv, struct v4l2_control *control, int val_signed) {
    struct v4l2_queryctrl	qctrl;

    qctrl.id = control->id;
    if (ioctl(priv->video_fd, VIDIOC_QUERYCTRL, &qctrl) < 0) {
	mp_msg(MSGT_TV, MSGL_ERR, "%s: ioctl query control failed: %s\n",
	 info.short_name, strerror(errno));
	return TVI_CONTROL_FALSE;
    }

    if (val_signed) {
	if (control->value < 0) {
	    control->value = qctrl.default_value + control->value *
		(qctrl.default_value - qctrl.minimum) / 100;
	} else {
	    control->value = qctrl.default_value + control->value *
		(qctrl.maximum - qctrl.default_value) / 100;
	}
    } else {
	if (control->value < 50) {
	    control->value = qctrl.default_value + (control->value-50) *
		(qctrl.default_value - qctrl.minimum) / 50;
	} else {
	    control->value = qctrl.default_value + (control->value-50) *
		(qctrl.maximum - qctrl.default_value) / 50;
	}
    }
    

    if (ioctl(priv->video_fd, VIDIOC_S_CTRL, control) < 0) {
	mp_msg(MSGT_TV, MSGL_ERR,"%s: ioctl set %s %d failed: %s\n",
	 info.short_name, qctrl.name, control->value, strerror(errno));
	return TVI_CONTROL_FALSE;
    }
    mp_msg(MSGT_TV, MSGL_V, "%s: set %s: %d [%d, %d]\n", info.short_name,
     qctrl.name, control->value, qctrl.minimum, qctrl.maximum);

    return TVI_CONTROL_TRUE;
}


/*
** Scale the control values back to what mplayer needs.
*/
static int get_control(priv_t *priv, struct v4l2_control *control, int val_signed) {
    struct v4l2_queryctrl	qctrl;

    qctrl.id = control->id;
    if (ioctl(priv->video_fd, VIDIOC_QUERYCTRL, &qctrl) < 0) {
	mp_msg(MSGT_TV, MSGL_ERR, "%s: ioctl query control failed: %s\n",
	 info.short_name, strerror(errno));
	return TVI_CONTROL_FALSE;
    }

    if (ioctl(priv->video_fd, VIDIOC_G_CTRL, control) < 0) {
	mp_msg(MSGT_TV, MSGL_ERR,"%s: ioctl get %s failed: %s\n",
	 info.short_name, qctrl.name, strerror(errno));
	return TVI_CONTROL_FALSE;
    }
    mp_msg(MSGT_TV, MSGL_V, "%s: get %s: %d [%d, %d]\n", info.short_name,
     qctrl.name, control->value, qctrl.minimum, qctrl.maximum);

    if (val_signed) {
	if (control->value < qctrl.default_value) {
	    control->value = (control->value - qctrl.default_value) * 100 /
		(qctrl.default_value - qctrl.minimum);
	} else {
	    control->value = (control->value - qctrl.default_value) * 100 /
		(qctrl.maximum - qctrl.default_value);
	}
    } else {
	if (control->value < qctrl.default_value) {
	    control->value = (control->value - qctrl.default_value) * 50 /
		(qctrl.default_value - qctrl.minimum) + 50;
	} else {
	    control->value = (control->value - qctrl.default_value) * 50 /
		(qctrl.maximum - qctrl.default_value) + 50;
	}
    }

    return TVI_CONTROL_TRUE;
}

static int control(priv_t *priv, int cmd, void *arg)
{
    struct v4l2_control control;
    struct v4l2_frequency frequency;

    switch(cmd) {
    case TVI_CONTROL_IS_AUDIO:
	if (tv_param_force_audio) return TVI_CONTROL_TRUE;
	return priv->input.audioset ? TVI_CONTROL_TRUE: TVI_CONTROL_FALSE;
    case TVI_CONTROL_IS_VIDEO:
	return priv->capability.capabilities & V4L2_CAP_VIDEO_CAPTURE?
	    TVI_CONTROL_TRUE: TVI_CONTROL_FALSE;
    case TVI_CONTROL_IS_TUNER:
	return priv->capability.capabilities & V4L2_CAP_TUNER?
	    TVI_CONTROL_TRUE: TVI_CONTROL_FALSE;
    case TVI_CONTROL_IMMEDIATE:
	priv->immediate_mode = 1;
	return TVI_CONTROL_TRUE;
    case TVI_CONTROL_VID_GET_FPS:
	*(float *)arg = priv->standard.frameperiod.denominator /
	    priv->standard.frameperiod.numerator;
	mp_msg(MSGT_TV, MSGL_V, "%s: get fps: %f\n", info.short_name,
	       *(float *)arg);
	return TVI_CONTROL_TRUE;
    case TVI_CONTROL_VID_GET_BITS:
	if (getfmt(priv) < 0) return TVI_CONTROL_FALSE;
	*(int *)arg = pixfmt2depth(priv->format.fmt.pix.pixelformat);
	mp_msg(MSGT_TV, MSGL_V, "%s: get depth: %d\n", info.short_name,
	       *(int *)arg);
	return TVI_CONTROL_TRUE;
    case TVI_CONTROL_VID_GET_FORMAT:
	if (getfmt(priv) < 0) return TVI_CONTROL_FALSE;
	if (priv->mp_format == IMGFMT_YV12 && priv->format.fmt.pix.pixelformat == V4L2_PIX_FMT_YUV420) {
	    *(int *)arg = IMGFMT_YV12;
	} else {
	    *(int *)arg = fcc_vl2mp(priv->format.fmt.pix.pixelformat);
	}
	mp_msg(MSGT_TV, MSGL_V, "%s: get format: %s\n", info.short_name,
	       pixfmt2name(priv->format.fmt.pix.pixelformat));
	return TVI_CONTROL_TRUE;
    case TVI_CONTROL_VID_SET_FORMAT:
	if (getfmt(priv) < 0) return TVI_CONTROL_FALSE;
	priv->format.fmt.pix.pixelformat = fcc_mp2vl(*(int *)arg);
	priv->format.fmt.pix.field = V4L2_FIELD_ANY;
	    
	priv->mp_format = *(int *)arg;
	mp_msg(MSGT_TV, MSGL_V, "%s: set format: %s\n", info.short_name,
	       pixfmt2name(priv->format.fmt.pix.pixelformat));
	if (ioctl(priv->video_fd, VIDIOC_S_FMT, &priv->format) < 0) {
	    mp_msg(MSGT_TV, MSGL_ERR, "%s: ioctl set format failed: %s\n",
		   info.short_name, strerror(errno));
	    return TVI_CONTROL_FALSE;
	}
	return TVI_CONTROL_TRUE;
    case TVI_CONTROL_VID_GET_WIDTH:
	if (getfmt(priv) < 0) return TVI_CONTROL_FALSE;
	*(int *)arg = priv->format.fmt.pix.width;
	mp_msg(MSGT_TV, MSGL_V, "%s: get width: %d\n", info.short_name,
	       *(int *)arg);
	return TVI_CONTROL_TRUE;
    case TVI_CONTROL_VID_CHK_WIDTH:
	return TVI_CONTROL_TRUE;
    case TVI_CONTROL_VID_SET_WIDTH:
	if (getfmt(priv) < 0) return TVI_CONTROL_FALSE;
	priv->format.fmt.pix.width = *(int *)arg;
	mp_msg(MSGT_TV, MSGL_V, "%s: set width: %d\n", info.short_name,
	       *(int *)arg);
	if (ioctl(priv->video_fd, VIDIOC_S_FMT, &priv->format) < 0) {
	    mp_msg(MSGT_TV, MSGL_ERR, "%s: ioctl set width failed: %s\n",
		   info.short_name, strerror(errno));
	    return TVI_CONTROL_FALSE;
	}
	return TVI_CONTROL_TRUE;
    case TVI_CONTROL_VID_GET_HEIGHT:
	if (getfmt(priv) < 0) return TVI_CONTROL_FALSE;
	*(int *)arg = priv->format.fmt.pix.height;
	mp_msg(MSGT_TV, MSGL_V, "%s: get height: %d\n", info.short_name,
	       *(int *)arg);
	return TVI_CONTROL_TRUE;
    case TVI_CONTROL_VID_CHK_HEIGHT:
	return TVI_CONTROL_TRUE;
    case TVI_CONTROL_VID_SET_HEIGHT:
	if (getfmt(priv) < 0) return TVI_CONTROL_FALSE;
	priv->format.fmt.pix.height = *(int *)arg;
	mp_msg(MSGT_TV, MSGL_V, "%s: set height: %d\n", info.short_name,
	       *(int *)arg);
	if (ioctl(priv->video_fd, VIDIOC_S_FMT, &priv->format) < 0) {
	    mp_msg(MSGT_TV, MSGL_ERR, "%s: ioctl set height failed: %s\n",
		   info.short_name, strerror(errno));
	    return TVI_CONTROL_FALSE;
	}
	return TVI_CONTROL_TRUE;
	case TVI_CONTROL_VID_GET_BRIGHTNESS:
	    control.id = V4L2_CID_BRIGHTNESS;
	    if (get_control(priv, &control, 1) == TVI_CONTROL_TRUE) {
		*(int *)arg = control.value;
		return TVI_CONTROL_TRUE;
	    }
	    return TVI_CONTROL_FALSE;
	case TVI_CONTROL_VID_SET_BRIGHTNESS:
	    control.id = V4L2_CID_BRIGHTNESS;
	    control.value = *(int *)arg;
	    return set_control(priv, &control, 1);
	case TVI_CONTROL_VID_GET_HUE:
	    control.id = V4L2_CID_HUE;
	    if (get_control(priv, &control, 1) == TVI_CONTROL_TRUE) {
		*(int *)arg = control.value;
		return TVI_CONTROL_TRUE;
	    }
	    return TVI_CONTROL_FALSE;
	case TVI_CONTROL_VID_SET_HUE:
	    control.id = V4L2_CID_HUE;
	    control.value = *(int *)arg;
	    return set_control(priv, &control, 1);
	case TVI_CONTROL_VID_GET_SATURATION:
	    control.id = V4L2_CID_SATURATION;
	    if (get_control(priv, &control, 1) == TVI_CONTROL_TRUE) {
		*(int *)arg = control.value;
		return TVI_CONTROL_TRUE;
	    }
	    return TVI_CONTROL_FALSE;
	case TVI_CONTROL_VID_SET_SATURATION:
	    control.id = V4L2_CID_SATURATION;
	    control.value = *(int *)arg;
	    return set_control(priv, &control, 1);
	case TVI_CONTROL_VID_GET_CONTRAST:
	    control.id = V4L2_CID_CONTRAST;
	    if (get_control(priv, &control, 1) == TVI_CONTROL_TRUE) {
		*(int *)arg = control.value;
		return TVI_CONTROL_TRUE;
	    }
	    return TVI_CONTROL_FALSE;
	case TVI_CONTROL_VID_SET_CONTRAST:
	    control.id = V4L2_CID_CONTRAST;
	    control.value = *(int *)arg;
	    return set_control(priv, &control, 1);
    case TVI_CONTROL_TUN_GET_FREQ:
	frequency.tuner = 0;
	frequency.type  = V4L2_TUNER_ANALOG_TV;
	if (ioctl(priv->video_fd, VIDIOC_G_FREQUENCY, &frequency) < 0) {
	    mp_msg(MSGT_TV,MSGL_ERR,"%s: ioctl get frequency failed: %s\n",
		   info.short_name, strerror(errno));
	    return TVI_CONTROL_FALSE;
	}
	*(int *)arg = frequency.frequency;
	return TVI_CONTROL_TRUE;
    case TVI_CONTROL_TUN_SET_FREQ:
#if 0
	if (priv->input.audioset) {
	    set_mute(priv, 1);
	    usleep(100000); // wait to supress noise during switching
	}
#endif
	frequency.tuner = 0;
	frequency.type  = V4L2_TUNER_ANALOG_TV;
	frequency.frequency = *(int *)arg;
	if (ioctl(priv->video_fd, VIDIOC_S_FREQUENCY, &frequency) < 0) {
	    mp_msg(MSGT_TV,MSGL_ERR,"%s: ioctl set frequency failed: %s\n",
		   info.short_name, strerror(errno));
	    return TVI_CONTROL_FALSE;
	}
#if 0
	if (priv->input.audioset) {
	    usleep(100000); // wait to supress noise during switching
	    set_mute(priv, 0);
	}
#endif
	return TVI_CONTROL_TRUE;
    case TVI_CONTROL_TUN_GET_TUNER:
	mp_msg(MSGT_TV, MSGL_V, "%s: get tuner\n");
	if (ioctl(priv->video_fd, VIDIOC_G_TUNER, &priv->tuner) < 0) {
	    mp_msg(MSGT_TV, MSGL_ERR, "%s: ioctl get tuner failed: %s\n",
		   info.short_name, strerror(errno));
	    return TVI_CONTROL_FALSE;
	}
	return TVI_CONTROL_TRUE;
    case TVI_CONTROL_TUN_SET_TUNER:
	mp_msg(MSGT_TV, MSGL_V, "%s: set tuner\n");
	if (ioctl(priv->video_fd, VIDIOC_S_TUNER, &priv->tuner) < 0) {
	    mp_msg(MSGT_TV, MSGL_ERR, "%s: ioctl set tuner failed: %s\n",
		   info.short_name, strerror(errno));
	    return TVI_CONTROL_FALSE;
	}
	return TVI_CONTROL_TRUE;
    case TVI_CONTROL_TUN_GET_NORM:
	*(int *)arg = priv->standard.index;
	return TVI_CONTROL_TRUE;
    case TVI_CONTROL_TUN_SET_NORM:
	priv->standard.index = *(int *)arg;
	if (ioctl(priv->video_fd, VIDIOC_ENUMSTD, &priv->standard) < 0) {
	    mp_msg(MSGT_TV, MSGL_ERR, "%s: ioctl enum norm failed: %s\n",
		   info.short_name, strerror(errno));
	    return TVI_CONTROL_FALSE;
	}
	mp_msg(MSGT_TV, MSGL_V, "%s: set norm: %s\n", info.short_name, priv->standard.name);
	if (ioctl(priv->video_fd, VIDIOC_S_STD, &priv->standard.id) < 0) {
	    mp_msg(MSGT_TV, MSGL_ERR, "%s: ioctl set norm failed: %s\n",
		   info.short_name, strerror(errno));
	    return TVI_CONTROL_FALSE;
	}
	return TVI_CONTROL_TRUE;
    case TVI_CONTROL_SPC_GET_INPUT:
	if (ioctl(priv->video_fd, VIDIOC_G_INPUT, (int *)arg) < 0) {
	    mp_msg(MSGT_TV, MSGL_ERR, "%s: ioctl get input failed: %s\n",
		   info.short_name, strerror(errno));
	    return TVI_CONTROL_FALSE;
	}
	return TVI_CONTROL_TRUE;
    case TVI_CONTROL_SPC_SET_INPUT:
	mp_msg(MSGT_TV, MSGL_V, "%s: set input: %d\n", info.short_name, *(int *)arg);
	priv->input.index = *(int *)arg;
	if (ioctl(priv->video_fd, VIDIOC_ENUMINPUT, &priv->input) < 0) {
	    mp_msg(MSGT_TV, MSGL_ERR, "%s: ioctl enum input failed: %s\n",
		   info.short_name, strerror(errno));
	    return TVI_CONTROL_FALSE;
	}
	if (ioctl(priv->video_fd, VIDIOC_S_INPUT, (int *)arg) < 0) {
	    mp_msg(MSGT_TV, MSGL_ERR, "%s: ioctl set input failed: %s\n",
		   info.short_name, strerror(errno));
	    return TVI_CONTROL_FALSE;
	}
	return TVI_CONTROL_TRUE;
    case TVI_CONTROL_AUD_GET_FORMAT:
	*(int *)arg = AFMT_S16_LE;
	mp_msg(MSGT_TV, MSGL_V, "%s: get audio format: %d\n",
	       info.short_name, *(int *)arg);
	return TVI_CONTROL_TRUE;
    case TVI_CONTROL_AUD_GET_SAMPLERATE:
	*(int *)arg = priv->audio_in.samplerate;
	mp_msg(MSGT_TV, MSGL_V, "%s: get audio samplerate: %d\n",
	       info.short_name, *(int *)arg);
	return TVI_CONTROL_TRUE;
    case TVI_CONTROL_AUD_GET_SAMPLESIZE:
	*(int *)arg = priv->audio_in.bytes_per_sample;;
	mp_msg(MSGT_TV, MSGL_V, "%s: get audio samplesize: %d\n",
	       info.short_name, *(int *)arg);
	return TVI_CONTROL_TRUE;
    case TVI_CONTROL_AUD_GET_CHANNELS:
	*(int *)arg = priv->audio_in.channels;
	mp_msg(MSGT_TV, MSGL_V, "%s: get audio channels: %d\n",
	       info.short_name, *(int *)arg);
	return TVI_CONTROL_TRUE;
    case TVI_CONTROL_AUD_SET_SAMPLERATE:
	mp_msg(MSGT_TV, MSGL_V, "%s: set audio samplerate: %d\n",
	       info.short_name, *(int *)arg);
	if (audio_in_set_samplerate(&priv->audio_in, (int)*(void **)arg) < 0) return TVI_CONTROL_FALSE;
//	setup_audio_buffer_sizes(priv);
	return TVI_CONTROL_TRUE;
    }
    mp_msg(MSGT_TV, MSGL_V, "%s: unknown control: %d\n", info.short_name, cmd);
    return(TVI_CONTROL_UNKNOWN);
}


#define PRIV ((priv_t *) (tvi_handle->priv))

/* handler creator - entry point ! */
tvi_handle_t *tvi_init_v4l2(char *video_dev, char *audio_dev)
{
    tvi_handle_t *tvi_handle;

    /* new_handle initializes priv with memset 0 */
    tvi_handle = new_handle();
    if (!tvi_handle) {
	return NULL;
    }
    PRIV->video_fd = -1;

    PRIV->video_dev = strdup(video_dev? video_dev: "/dev/video");
    if (!PRIV->video_dev) {
	free_handle(tvi_handle);
	return NULL;
    }

    if (audio_dev) {
	PRIV->audio_dev = strdup(audio_dev);
	if (!PRIV->audio_dev) {
	    free(PRIV->video_dev);
	    free_handle(tvi_handle);
	    return NULL;
	}
    }

    return tvi_handle;
}

#undef PRIV


static int uninit(priv_t *priv)
{
    int i, frames, dropped = 0;

    priv->shutdown = 1;
    pthread_join(priv->audio_grabber_thread, NULL);
    pthread_mutex_destroy(&priv->video_buffer_mutex);

    if (priv->streamon) {
	struct v4l2_buffer buf;

	/* get performance */
	frames = 1 + (priv->curr_frame - priv->first_frame) *
	    priv->standard.frameperiod.denominator /
	    priv->standard.frameperiod.numerator / 1000000;
	dropped = frames - priv->frames;

	/* turn off streaming */
	if (ioctl(priv->video_fd, VIDIOC_STREAMOFF, &(priv->map[0].buf.type)) < 0) {
	    mp_msg(MSGT_TV, MSGL_ERR, "%s: ioctl streamoff failed: %s\n",
		   info.short_name, strerror(errno));
	}
	priv->streamon = 0;

	/* unqueue all remaining buffers */
	memset(&buf,0,sizeof(buf));
	buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
	while (!ioctl(priv->video_fd, VIDIOC_DQBUF, &buf));
    }

    /* unmap all buffers */
    for (i = 0; i < priv->mapcount; i++) {
	if (munmap(priv->map[i].addr, priv->map[i].len) < 0) {
	    mp_msg(MSGT_TV, MSGL_ERR, "%s: munmap capture buffer failed: %s\n",
		   info.short_name, strerror(errno));
	}
    }

    /* stop audio thread */
    if (!tv_param_noaudio) {
	pthread_join(priv->audio_grabber_thread, NULL);
	pthread_mutex_destroy(&priv->skew_mutex);
    }

    if (priv->input.audioset) {
	set_mute(priv, 1);
    }

    /* free memory and close device */
    free(priv->map);		priv->map = NULL;
    priv->mapcount = 0;
    close(priv->video_fd);	priv->video_fd  = -1;
    free(priv->video_dev);	priv->video_dev = NULL;

    if (priv->video_ringbuffer) {
	int i;
	for (i = 0; i < priv->video_buffer_size_current; i++) {
	    free(priv->video_ringbuffer[i]);
	}
	free(priv->video_ringbuffer);
    }
    if (priv->video_timebuffer)
	free(priv->video_timebuffer);
    if (!tv_param_noaudio) {
	if (priv->audio_ringbuffer)
	    free(priv->audio_ringbuffer);
	if (priv->audio_skew_buffer)
	    free(priv->audio_skew_buffer);
    }

    /* show some nice statistics ;-) */
    mp_msg(MSGT_TV, MSGL_INFO,
	   "%s: %d frames successfully processed, %d frames dropped.\n",
	   info.short_name, priv->frames, dropped);
    mp_msg(MSGT_TV, MSGL_V, "%s: up to %u video frames buffered.\n",
	   info.short_name, priv->video_buffer_size_current);
    return 1;
}


/* initialisation */
static int init(priv_t *priv)
{
    int i;

    if (tv_param_immediate == 1)
	tv_param_noaudio = 1;

    priv->audio_ringbuffer = NULL;
    priv->audio_skew_buffer = NULL;

    /* Open the video device. */
    priv->video_fd = open(priv->video_dev, O_RDWR);
    if (priv->video_fd < 0) {
	mp_msg(MSGT_TV, MSGL_ERR, "%s: unable to open '%s': %s\n",
	       info.short_name, priv->video_dev, strerror(errno));
	uninit(priv);
	return 0;
    }
    mp_msg(MSGT_TV, MSGL_DBG2, "%s: video fd: %s: %d\n",
	   info.short_name, priv->video_dev, priv->video_fd);

    /*
    ** Query the video capabilities and current settings
    ** for further control calls.
    */
    if (ioctl(priv->video_fd, VIDIOC_QUERYCAP, &priv->capability) < 0) {
	mp_msg(MSGT_TV, MSGL_ERR, "%s: ioctl query capabilities failed: %s\n",
	       info.short_name, strerror(errno));
	uninit(priv);
	return 0;
    }

    if (!(priv->capability.capabilities & V4L2_CAP_VIDEO_CAPTURE))
    {
	mp_msg(MSGT_TV, MSGL_ERR, "Device %s is not a video capture device.\n",
	       priv->video_dev);
	return 0;
    }

    if (getfmt(priv) < 0 || getstd(priv) < 0) {
	uninit(priv);
	return 0;
    }
    /*
    ** if this device has got a tuner query it's settings
    ** otherwise set some nice defaults
    */
    if (priv->capability.capabilities & V4L2_CAP_TUNER) {
	if (ioctl(priv->video_fd, VIDIOC_G_TUNER, &priv->tuner) < 0) {
	    mp_msg(MSGT_TV, MSGL_ERR, "%s: ioctl get tuner failed: %s\n",
		   info.short_name, strerror(errno));
	    uninit(priv);
	    return 0;
	}
    }
    mp_msg(MSGT_TV, MSGL_INFO, "Selected device: %s\n", priv->capability.card);
    if (priv->capability.capabilities & V4L2_CAP_TUNER) {
	mp_msg(MSGT_TV, MSGL_INFO, " Tuner cap:%s%s%s\n",
		(priv->tuner.capability & V4L2_TUNER_CAP_STEREO) ? " STEREO" : "",
		(priv->tuner.capability & V4L2_TUNER_CAP_LANG1)  ? " LANG1"  : "",
		(priv->tuner.capability & V4L2_TUNER_CAP_LANG2)  ? " LANG2"  : "");
	mp_msg(MSGT_TV, MSGL_INFO, " Tuner rxs:%s%s%s%s\n",
		(priv->tuner.rxsubchans & V4L2_TUNER_SUB_MONO)   ? " MONO"   : "",
		(priv->tuner.rxsubchans & V4L2_TUNER_SUB_STEREO) ? " STEREO" : "",
		(priv->tuner.rxsubchans & V4L2_TUNER_SUB_LANG1)  ? " LANG1"  : "",
		(priv->tuner.rxsubchans & V4L2_TUNER_SUB_LANG2)  ? " LANG2"  : "");
    }
    mp_msg(MSGT_TV, MSGL_INFO, " Capabilites:%s%s%s%s%s%s%s%s%s%s%s\n",
	   priv->capability.capabilities & V4L2_CAP_VIDEO_CAPTURE?
	   "  video capture": "",
	   priv->capability.capabilities & V4L2_CAP_VIDEO_OUTPUT?
	   "  video output": "",
	   priv->capability.capabilities & V4L2_CAP_VIDEO_OVERLAY?
	   "  video overlay": "",
	   priv->capability.capabilities & V4L2_CAP_VBI_CAPTURE?
	   "  VBI capture device": "",
	   priv->capability.capabilities & V4L2_CAP_VBI_OUTPUT?
	   "  VBI output": "",
	   priv->capability.capabilities & V4L2_CAP_RDS_CAPTURE?
	   "  RDS data capture": "",
	   priv->capability.capabilities & V4L2_CAP_TUNER?
	   "  tuner": "",
	   priv->capability.capabilities & V4L2_CAP_AUDIO?
	   "  audio": "",
	   priv->capability.capabilities & V4L2_CAP_READWRITE?
	   "  read/write": "",
	   priv->capability.capabilities & V4L2_CAP_ASYNCIO?
	   "  async i/o": "",
	   priv->capability.capabilities & V4L2_CAP_STREAMING?
	   "  streaming": "");
    mp_msg(MSGT_TV, MSGL_INFO, " supported norms:");
    for (i = 0;; i++) {
	struct v4l2_standard standard;
	memset(&standard, 0, sizeof(standard));
	standard.index = i;
	if (-1 == ioctl(priv->video_fd, VIDIOC_ENUMSTD, &standard))
	    break;
	printf(" %d = %s;", i, standard.name);
    }
    mp_msg(MSGT_TV, MSGL_INFO, "\n inputs:");
    for (i = 0; 1; i++) {
	struct v4l2_input input;

	input.index = i;
	if (ioctl(priv->video_fd, VIDIOC_ENUMINPUT, &input) < 0) {
	    break;
	}
	mp_msg(MSGT_TV, MSGL_INFO, " %d = %s;", i, input.name);
    }
    if (ioctl(priv->video_fd, VIDIOC_G_INPUT, &i) < 0) {
	mp_msg(MSGT_TV, MSGL_ERR, "%s: ioctl get input failed: %s\n",
	       info.short_name, strerror(errno));
    }
    mp_msg(MSGT_TV, MSGL_INFO, "\n Current input: %d\n", i);
    for (i = 0; ; i++) {
	struct v4l2_fmtdesc fmtdesc;

	fmtdesc.index = i;
	fmtdesc.type  = V4L2_BUF_TYPE_VIDEO_CAPTURE;
	if (ioctl(priv->video_fd, VIDIOC_ENUM_FMT, &fmtdesc) < 0) {
	    break;
	}
	mp_msg(MSGT_TV, MSGL_V, " Format %-6s (%2d bits, %s): %s\n",
	       pixfmt2name(fmtdesc.pixelformat), pixfmt2depth(fmtdesc.pixelformat),
	       fmtdesc.description, vo_format_name(fcc_vl2mp(fmtdesc.pixelformat)));
    }
    mp_msg(MSGT_TV, MSGL_INFO, " Current format: %s\n",
	   pixfmt2name(priv->format.fmt.pix.pixelformat));

    /* set some nice defaults */
    if (getfmt(priv) < 0) return 0;
    priv->format.fmt.pix.width  = 640;
    priv->format.fmt.pix.height = 480;
    if (ioctl(priv->video_fd, VIDIOC_S_FMT, &priv->format) < 0) {
	mp_msg(MSGT_TV, MSGL_ERR, "%s: ioctl set format failed: %s\n",
	       info.short_name, strerror(errno));
	uninit(priv);
	return 0;
    }

//    if (!(priv->capability.capabilities & V4L2_CAP_AUDIO) && !tv_param_force_audio) tv_param_noaudio = 1;

    if (priv->capability.capabilities & V4L2_CAP_TUNER) {
	struct v4l2_control control;
	if (tv_param_amode >= 0) {
	    mp_msg(MSGT_TV, MSGL_V, "%s: setting audio mode\n", info.short_name);
	    priv->tuner.audmode = amode2v4l(tv_param_amode);
	    if (ioctl(priv->video_fd, VIDIOC_S_TUNER, &priv->tuner) < 0) {
		mp_msg(MSGT_TV, MSGL_ERR, "%s: ioctl set tuner failed: %s\n",
		       info.short_name, strerror(errno));
		return TVI_CONTROL_FALSE;
	    }
	}
	mp_msg(MSGT_TV, MSGL_INFO, "%s: current audio mode is :%s%s%s%s\n", info.short_name,
		(priv->tuner.audmode == V4L2_TUNER_MODE_MONO)   ? " MONO"   : "",
		(priv->tuner.audmode == V4L2_TUNER_MODE_STEREO) ? " STEREO" : "",
		(priv->tuner.audmode == V4L2_TUNER_MODE_LANG1)  ? " LANG1"  : "",
		(priv->tuner.audmode == V4L2_TUNER_MODE_LANG2)  ? " LANG2"  : "");

	if (tv_param_volume >= 0) {
	    control.id = V4L2_CID_AUDIO_VOLUME;
	    control.value = tv_param_volume;
	    set_control(priv, &control, 0);
	}
	if (tv_param_bass >= 0) {
	    control.id = V4L2_CID_AUDIO_BASS;
	    control.value = tv_param_bass;
	    set_control(priv, &control, 0);
	}
	if (tv_param_treble >= 0) {
	    control.id = V4L2_CID_AUDIO_TREBLE;
	    control.value = tv_param_treble;
	    set_control(priv, &control, 0);
	}
	if (tv_param_balance >= 0) {
	    control.id = V4L2_CID_AUDIO_BALANCE;
	    control.value = tv_param_balance;
	    set_control(priv, &control, 0);
	}
    }
    
    /* audio init */
    if (!tv_param_noaudio) {
#ifdef HAVE_ALSA9
	if (tv_param_alsa)
	    audio_in_init(&priv->audio_in, AUDIO_IN_ALSA);
	else
	    audio_in_init(&priv->audio_in, AUDIO_IN_OSS);
#else
	audio_in_init(&priv->audio_in, AUDIO_IN_OSS);
#endif

	if (priv->audio_dev) {
	    audio_in_set_device(&priv->audio_in, priv->audio_dev);
	}

	audio_in_set_samplerate(&priv->audio_in, 44100);
	if (priv->capability.capabilities & V4L2_CAP_TUNER) {
	    if (priv->tuner.audmode == V4L2_TUNER_MODE_STEREO) {
		audio_in_set_channels(&priv->audio_in, 2);
	    } else {
		audio_in_set_channels(&priv->audio_in, 1);
	    }
	} else {
	    if (tv_param_forcechan >= 0) {
		audio_in_set_channels(&priv->audio_in, tv_param_forcechan);
	    } else {
		audio_in_set_channels(&priv->audio_in, 2);
	    }
	}
	if (audio_in_setup(&priv->audio_in) < 0) return 0;
//	setup_audio_buffer_sizes(priv);
    }

    return 1;
}

static int get_capture_buffer_size(priv_t *priv)
{
    int bufsize, cnt;
    int w = priv->format.fmt.pix.width;
    int h = priv->format.fmt.pix.height;
    int d = pixfmt2depth(priv->format.fmt.pix.pixelformat);
    int bytesperline = w*d/8;

    if (tv_param_buffer_size >= 0) {
	bufsize = tv_param_buffer_size*1024*1024;
    } else {
#ifdef HAVE_SYS_SYSINFO_H
	struct sysinfo si;
	
	sysinfo(&si);
	if (si.totalram<2*1024*1024) {
	    bufsize = 1024*1024;
	} else {
	    bufsize = si.totalram/2;
	}
#else
	bufsize = 16*1024*1024;
#endif
    }
    
    cnt = bufsize/(h*bytesperline);
    if (cnt < 2) cnt = 2;
    
    return cnt;
}

/* that's the real start, we'got the format parameters (checked with control) */
static int start(priv_t *priv)
{
    struct v4l2_requestbuffers request;
    int i;

    /* setup audio parameters */

    /* we need this to size the audio buffer properly */
    if (priv->immediate_mode) {
	priv->video_buffer_size_max = 2;
    } else {
	priv->video_buffer_size_max = get_capture_buffer_size(priv);
    }
    
    if (!tv_param_noaudio) {
	setup_audio_buffer_sizes(priv);
	priv->audio_skew_buffer = (long long*)malloc(sizeof(long long)*priv->aud_skew_cnt);
	if (!priv->audio_skew_buffer) {
	    mp_msg(MSGT_TV, MSGL_ERR, "cannot allocate skew buffer: %s\n", strerror(errno));
	    return 0;
	}

	priv->audio_ringbuffer = (unsigned char*)malloc(priv->audio_in.blocksize*priv->audio_buffer_size);
	if (!priv->audio_ringbuffer) {
	    mp_msg(MSGT_TV, MSGL_ERR, "cannot allocate audio buffer: %s\n", strerror(errno));
	    return 0;
	}

	priv->audio_secs_per_block = (double)priv->audio_in.blocksize/(priv->audio_in.samplerate
								    *priv->audio_in.channels
								    *priv->audio_in.bytes_per_sample);
	priv->audio_head = 0;
	priv->audio_tail = 0;
	priv->audio_cnt = 0;
	priv->audio_drop = 0;
	priv->audio_skew = 0;
	priv->audio_skew_total = 0;
	priv->audio_recv_blocks_total = 0;
	priv->audio_sent_blocks_total = 0;
    }

    /* setup video parameters */
    if (!tv_param_noaudio) {
	if (priv->video_buffer_size_max < 3.0*(priv->standard.frameperiod.denominator /
					       priv->standard.frameperiod.numerator)
	    *priv->audio_secs_per_block) {
	    mp_msg(MSGT_TV, MSGL_ERR, "Video buffer shorter than 3 times audio frame duration.\n"
		   "You will probably experience heavy framedrops.\n");
	}
    }
    
    {
	int bytesperline = priv->format.fmt.pix.width*pixfmt2depth(priv->format.fmt.pix.pixelformat)/8;
	
	mp_msg(MSGT_TV, MSGL_V, "Using a ring buffer for maximum %d frames, %d MB total size.\n",
	       priv->video_buffer_size_max,
	       priv->video_buffer_size_max*priv->format.fmt.pix.height*bytesperline/(1024*1024));
    }

    priv->video_ringbuffer = (unsigned char**)malloc(priv->video_buffer_size_max*sizeof(unsigned char*));
    if (!priv->video_ringbuffer) {
	mp_msg(MSGT_TV, MSGL_ERR, "cannot allocate video buffer: %s\n", strerror(errno));
	return 0;
    }
    for (i = 0; i < priv->video_buffer_size_max; i++)
	priv->video_ringbuffer[i] = NULL;
    priv->video_timebuffer = (long long*)malloc(sizeof(long long) * priv->video_buffer_size_max);
    if (!priv->video_timebuffer) {
	mp_msg(MSGT_TV, MSGL_ERR, "cannot allocate time buffer: %s\n", strerror(errno));
	return 0;
    }

    priv->video_head = 0;
    priv->video_tail = 0;
    priv->video_cnt = 0;
    
    /* request buffers */
    if (priv->immediate_mode) {
	request.count = 2;
    } else {
	request.count = BUFFER_COUNT;
    }
    
    request.type  = V4L2_BUF_TYPE_VIDEO_CAPTURE;
    request.memory = V4L2_MEMORY_MMAP;
    if (ioctl(priv->video_fd, VIDIOC_REQBUFS, &request) < 0) {
	mp_msg(MSGT_TV, MSGL_ERR, "%s: ioctl request buffers failed: %s\n",
	       info.short_name, strerror(errno));
	return 0;
    }

    /* query buffers */
    if (!(priv->map = malloc(sizeof(struct map) * request.count))) {
	mp_msg(MSGT_TV, MSGL_ERR, "%s: malloc capture buffers failed: %s\n",
	       info.short_name, strerror(errno));
	return 0;
    }

    /* map and queue buffers */
    for (i = 0; i < request.count; i++) {
	memset(&priv->map[i].buf,0,sizeof(priv->map[i].buf));
	priv->map[i].buf.index = i;
	priv->map[i].buf.type  = V4L2_BUF_TYPE_VIDEO_CAPTURE;
	priv->map[i].buf.memory  = V4L2_MEMORY_MMAP;
	if (ioctl(priv->video_fd, VIDIOC_QUERYBUF, &(priv->map[i].buf)) < 0) {
	    mp_msg(MSGT_TV, MSGL_ERR, "%s: ioctl query buffer failed: %s\n",
		   info.short_name, strerror(errno));
	    free(priv->map);
	    priv->map = NULL;
	    return 0;
	}
	priv->map[i].addr = mmap (0, priv->map[i].buf.length, PROT_READ |
				  PROT_WRITE, MAP_SHARED, priv->video_fd, priv->map[i].buf.m.offset);
	if (priv->map[i].addr == MAP_FAILED) {
	    mp_msg(MSGT_TV, MSGL_ERR, "%s: mmap capture buffer failed: %s\n",
		   info.short_name, strerror(errno));
	    priv->map[i].len = 0;
	    return 0;
	}
	priv->map[i].len = priv->map[i].buf.length;
	/* count up to make sure this is correct everytime */
	priv->mapcount++;

	if (ioctl(priv->video_fd, VIDIOC_QBUF, &(priv->map[i].buf)) < 0) {
	    mp_msg(MSGT_TV, MSGL_ERR, "%s: ioctl queue buffer failed: %s\n",
		   info.short_name, strerror(errno));
	    return 0;
	}
    }

    /* start audio thread */
    priv->shutdown = 0;
    priv->audio_skew_measure_time = 0;
    priv->first_frame = 0;
    priv->audio_skew = 0;
    priv->first = 1;

    if (priv->input.audioset) {
	set_mute(priv, 0);
    }
    
    return 1;
}


#ifdef HAVE_TV_BSDBT848
static double grabimmediate_video_frame(priv_t *priv, char *buffer, int len)
{
    memset(buffer, 0xCC, len);
    return(1);
}
#endif /* HAVE_TV_BSDBT848 */

// copies a video frame
// for YV12 swaps the 2nd and 3rd plane
static inline void copy_frame(priv_t *priv, unsigned char *dest, unsigned char *source)
{
    int w = priv->format.fmt.pix.width;
    int h = priv->format.fmt.pix.height;
    int d = pixfmt2depth(priv->format.fmt.pix.pixelformat);
    int bytesperline = w*d/8;

    // YV12 uses VIDEO_PALETTE_YUV420P, but the planes are swapped
    switch (priv->mp_format) {
    case IMGFMT_YV12:
	memcpy(dest, source, w * h);
	memcpy(dest+w * h*5/4, source+w * h, w * h/4);
	memcpy(dest+w * h, source+w * h*5/4, w * h/4);
	break;
    default:
	memcpy(dest, source, bytesperline * h);
    }
    
}

// maximum skew change, in frames
#define MAX_SKEW_DELTA 0.6
static void *video_grabber(void *data)
{
    priv_t *priv = (priv_t*)data;
    long long skew, prev_skew, xskew, interval, prev_interval;
    int i;
    int framesize = priv->format.fmt.pix.height*priv->format.fmt.pix.width*
	pixfmt2depth(priv->format.fmt.pix.pixelformat)/8;
    fd_set rdset;
    struct timeval timeout;
    struct v4l2_buffer buf;

    xskew = 0;
    skew = 0;
    interval = 0;
    prev_interval = 0;
    prev_skew = 0;

    mp_msg(MSGT_TV, MSGL_V, "%s: going to capture\n", info.short_name);
    if (ioctl(priv->video_fd, VIDIOC_STREAMON, &(priv->format.type)) < 0) {
	mp_msg(MSGT_TV, MSGL_ERR, "%s: ioctl streamon failed: %s\n",
	       info.short_name, strerror(errno));
	return 0;
    }
    priv->streamon = 1;

    if (!tv_param_noaudio) {
	pthread_mutex_init(&priv->skew_mutex, NULL);
	pthread_create(&priv->audio_grabber_thread, NULL, audio_grabber, priv);
    }

    for (priv->frames = 0; !priv->shutdown;)
    {
	int ret;
	
	if (priv->immediate_mode) {
	    while (priv->video_cnt == priv->video_buffer_size_max) {
		usleep(10000);
		if (priv->shutdown) {
		    return NULL;
		}
	    }
	}
		
	FD_ZERO (&rdset);
	FD_SET (priv->video_fd, &rdset);

	timeout.tv_sec = 1;
	timeout.tv_usec = 0;

	i = select(priv->video_fd + 1, &rdset, NULL, NULL, &timeout);
	if (i < 0) {
	    mp_msg(MSGT_TV, MSGL_ERR, "%s: select failed: %s\n",
		   info.short_name, strerror(errno));
	    continue;
	}
	else if (i == 0) {
	    mp_msg(MSGT_TV, MSGL_ERR, "%s: select timeout\n", info.short_name);
	    continue;
	}
	else if (!FD_ISSET(priv->video_fd, &rdset)) {
	    continue;
	}

	memset(&buf,0,sizeof(buf));
	buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
	ret = ioctl(priv->video_fd, VIDIOC_DQBUF, &buf);

	if (ret < 0) {
	    /*
	      if there's no signal, the buffer might me dequeued
	      so we query all the buffers to see which one we should
	      put back to queue

	      observed with saa7134 0.2.8
	      don't know if is it a bug or (mis)feature
	     */
	    mp_msg(MSGT_TV, MSGL_ERR, "%s: ioctl dequeue buffer failed: %s, idx = %d\n",
		   info.short_name, strerror(errno), buf.index);
	    for (i = 0; i < priv->mapcount; i++) {
		memset(&buf,0,sizeof(buf));
		buf.type = V4L2_BUF_TYPE_VIDEO_CAPTURE;
		buf.index = i;
		ret = ioctl(priv->video_fd, VIDIOC_QUERYBUF, &buf);
		if (ret < 0) {
		    mp_msg(MSGT_TV, MSGL_ERR, "%s: ioctl query buffer failed: %s, idx = %d\n",
			   info.short_name, strerror(errno), buf.index);
		    return 0;
		}
		if ((buf.flags & (V4L2_BUF_FLAG_QUEUED | V4L2_BUF_FLAG_MAPPED | V4L2_BUF_FLAG_DONE)) == V4L2_BUF_FLAG_MAPPED) {
		    if (ioctl(priv->video_fd, VIDIOC_QBUF, &(priv->map[i].buf)) < 0) {
			mp_msg(MSGT_TV, MSGL_ERR, "%s: ioctl queue buffer failed: %s\n",
			       info.short_name, strerror(errno));
			return 0;
		    }		
		}
	    }
	    continue;
	}

	/* store the timestamp of the very first frame as reference */
	if (!priv->frames++) {
	    priv->first_frame = (long long)1e6*buf.timestamp.tv_sec + buf.timestamp.tv_usec;
	}
	priv->curr_frame = (long long)buf.timestamp.tv_sec*1e6+buf.timestamp.tv_usec;
//	fprintf(stderr, "idx = %d, ts = %lf\n", buf.index, (double)(priv->curr_frame) / 1e6);

	interval = priv->curr_frame - priv->first_frame;

	if (!priv->immediate_mode) {
	    // interpolate the skew in time
	    pthread_mutex_lock(&priv->skew_mutex);
	    xskew = priv->audio_skew + (interval - priv->audio_skew_measure_time)*priv->audio_skew_factor;
	    pthread_mutex_unlock(&priv->skew_mutex);
 	    // correct extreme skew changes to avoid (especially) moving backwards in time
	    if (xskew - prev_skew > (interval - prev_interval)*MAX_SKEW_DELTA) {
		skew = prev_skew + (interval - prev_interval)*MAX_SKEW_DELTA;
	    } else if (xskew - prev_skew < -(interval - prev_interval)*MAX_SKEW_DELTA) {
		skew = prev_skew - (interval - prev_interval)*MAX_SKEW_DELTA;
	    } else {
		skew = xskew;
	    }
	}

	mp_msg(MSGT_TV, MSGL_DBG3, "\nfps = %lf, interval = %lf, a_skew = %f, corr_skew = %f\n",
	       (interval != prev_interval) ? (double)1e6/(interval - prev_interval) : -1,
	       (double)1e-6*interval, (double)1e-6*xskew, (double)1e-6*skew);
	mp_msg(MSGT_TV, MSGL_DBG3, "vcnt = %d, acnt = %d\n", priv->video_cnt, priv->audio_cnt);

	prev_skew = skew;
	prev_interval = interval;

	/* allocate a new buffer, if needed */
	pthread_mutex_lock(&priv->video_buffer_mutex);
	if (priv->video_buffer_size_current < priv->video_buffer_size_max) {
	    if (priv->video_cnt == priv->video_buffer_size_current) {
		unsigned char *newbuf = (unsigned char*)malloc(framesize);
		if (newbuf) {
		    memmove(priv->video_ringbuffer+priv->video_tail+1, priv->video_ringbuffer+priv->video_tail,
			    (priv->video_buffer_size_current-priv->video_tail)*sizeof(unsigned char *));
		    memmove(priv->video_timebuffer+priv->video_tail+1, priv->video_timebuffer+priv->video_tail,
			    (priv->video_buffer_size_current-priv->video_tail)*sizeof(long long));
		    priv->video_ringbuffer[priv->video_tail] = newbuf;
		    if ((priv->video_head >= priv->video_tail) && (priv->video_cnt > 0)) priv->video_head++;
		    priv->video_buffer_size_current++;
		}
	    }
	}
	pthread_mutex_unlock(&priv->video_buffer_mutex);

	if (priv->video_cnt == priv->video_buffer_size_current) {
	    if (!priv->immediate_mode) {
		mp_msg(MSGT_TV, MSGL_ERR, "\nvideo buffer full - dropping frame\n");
	    }
	} else {
	    if (priv->immediate_mode) {
		priv->video_timebuffer[priv->video_tail] = 0;
	    } else {
		// compensate for audio skew
		// negative skew => there are more audio samples, increase interval
		// positive skew => less samples, shorten the interval
		priv->video_timebuffer[priv->video_tail] = interval - skew;
	    }
		
	    copy_frame(priv, priv->video_ringbuffer[priv->video_tail], priv->map[buf.index].addr);
	    priv->video_tail = (priv->video_tail+1)%priv->video_buffer_size_current;
	    priv->video_cnt++;
	}
	if (ioctl(priv->video_fd, VIDIOC_QBUF, &buf) < 0) {
	    mp_msg(MSGT_TV, MSGL_ERR, "%s: ioctl queue buffer failed: %s\n",
		   info.short_name, strerror(errno));
	    return 0;
	}
    }
    return NULL;
}

static double grab_video_frame(priv_t *priv, char *buffer, int len)
{
    double interval;

    if (priv->first) {
	pthread_create(&priv->video_grabber_thread, NULL, video_grabber, priv);
	priv->first = 0;
    }

    while (priv->video_cnt == 0) {
	usleep(10000);
    }

    pthread_mutex_lock(&priv->video_buffer_mutex);
    interval = (double)priv->video_timebuffer[priv->video_head]*1e-6;
    memcpy(buffer, priv->video_ringbuffer[priv->video_head], len);
    priv->video_cnt--;
    priv->video_head = (priv->video_head+1)%priv->video_buffer_size_current;
    pthread_mutex_unlock(&priv->video_buffer_mutex);

    return interval;
}

static int get_video_framesize(priv_t *priv)
{
    return priv->format.fmt.pix.sizeimage;
}

/*
// for testing purposes only
static void read_doublespeed(priv_t *priv)
{
    char *bufx = (char*)malloc(priv->audio_in.blocksize*2);
    short *s;
    short *d;
    int i;
    
    audio_in_read_chunk(&priv->audio_in, bufx);
    audio_in_read_chunk(&priv->audio_in, bufx+priv->audio_in.blocksize);

    s = bufx;
    d = priv->audio_ringbuffer+priv->audio_tail*priv->audio_in.blocksize;
    for (i = 0; i < priv->audio_in.blocksize/2; i++) {
	*d++ = *s++;
	*s++;
    }
    
}
*/

static void *audio_grabber(void *data)
{
    priv_t *priv = (priv_t*)data;
    struct timeval tv;
    int i, audio_skew_ptr = 0;
    long long current_time, prev_skew = 0;

    gettimeofday(&tv, NULL);
    priv->audio_start_time = (long long)1e6*tv.tv_sec + tv.tv_usec;
    audio_in_start_capture(&priv->audio_in);
    for (i = 0; i < priv->aud_skew_cnt; i++)
	priv->audio_skew_buffer[i] = 0;

    for (; !priv->shutdown;)
    {
//	read_doublespeed(priv);
	if (audio_in_read_chunk(&priv->audio_in, priv->audio_ringbuffer+priv->audio_tail*priv->audio_in.blocksize) < 0)
	    continue;

	pthread_mutex_lock(&priv->skew_mutex);
	if (priv->first_frame == 0) {
	    // there is no first frame yet (unlikely to happen)
//	    fprintf(stderr, "warning - first frame not yet available!\n");
	    pthread_mutex_unlock(&priv->skew_mutex);
	    continue;
	}
	pthread_mutex_unlock(&priv->skew_mutex);

	gettimeofday(&tv, NULL);

	priv->audio_recv_blocks_total++;
	current_time = (long long)1e6*tv.tv_sec + tv.tv_usec - priv->audio_start_time;

//	fprintf(stderr, "spb = %lf, bs = %d, skew = %lf\n", priv->audio_secs_per_block, priv->audio_in.blocksize,
//		(double)(current_time - 1e6*priv->audio_secs_per_block*priv->audio_recv_blocks_total)/1e6);

	priv->audio_skew_total -= priv->audio_skew_buffer[audio_skew_ptr];
	priv->audio_skew_buffer[audio_skew_ptr] = current_time
	    - 1e6*priv->audio_secs_per_block*priv->audio_recv_blocks_total;
	priv->audio_skew_total += priv->audio_skew_buffer[audio_skew_ptr];
	audio_skew_ptr = (audio_skew_ptr+1) % priv->aud_skew_cnt;

	pthread_mutex_lock(&priv->skew_mutex);
	// linear interpolation - here we interpolate current skew value
	// from the moving average, which we expect to be in the middle
	// of the interval
	if (priv->audio_recv_blocks_total > priv->aud_skew_cnt) {
	    priv->audio_skew = priv->audio_skew_total/priv->aud_skew_cnt;
	    priv->audio_skew += (priv->audio_skew*priv->aud_skew_cnt)/(2*priv->audio_recv_blocks_total-priv->aud_skew_cnt);
	} else {
	    // this smoothens the evolution of audio_skew at startup a bit
	    priv->audio_skew = ((priv->aud_skew_cnt+priv->audio_recv_blocks_total)*priv->audio_skew_total)/(priv->aud_skew_cnt*priv->audio_recv_blocks_total);
	}
//	fprintf(stderr, "audio_skew = %lf\n", (double)priv->audio_skew/1e6);
	// current skew factor (assuming linearity)
	// used for further interpolation in video_grabber
	// probably overkill but seems to be necessary for
	// stress testing by dropping half of the audio frames ;)
	// especially when using ALSA with large block sizes
	// where audio_skew remains a long while behind
	if ((priv->audio_skew_measure_time != 0) && (current_time - priv->audio_skew_measure_time != 0)) {
	    priv->audio_skew_factor = (double)(priv->audio_skew-prev_skew)/(current_time - priv->audio_skew_measure_time);
	} else {
	    priv->audio_skew_factor = 0.0;
	}
	
	priv->audio_skew_measure_time = current_time;
	prev_skew = priv->audio_skew;
	priv->audio_skew -= priv->audio_start_time - priv->first_frame;
	pthread_mutex_unlock(&priv->skew_mutex);
	
	if ((priv->audio_tail+1) % priv->audio_buffer_size == priv->audio_head) {
	    mp_msg(MSGT_TV, MSGL_ERR, "\ntoo bad - dropping audio frame !\n");
	    priv->audio_drop++;
	} else {
	    priv->audio_tail = (priv->audio_tail+1) % priv->audio_buffer_size;
	    priv->audio_cnt++;
	}
    }
    return NULL;
}

static double grab_audio_frame(priv_t *priv, char *buffer, int len)
{
    mp_dbg(MSGT_TV, MSGL_DBG2, "grab_audio_frame(priv=%p, buffer=%p, len=%d)\n",
	priv, buffer, len);

    // compensate for dropped audio frames
    if (priv->audio_drop && (priv->audio_head == priv->audio_tail)) {
	priv->audio_drop--;
	priv->audio_sent_blocks_total++;
	memset(buffer, 0, len);
	return (double)priv->audio_sent_blocks_total*priv->audio_secs_per_block;
    }

    while (priv->audio_head == priv->audio_tail) {
	usleep(10000);
    }
    memcpy(buffer, priv->audio_ringbuffer+priv->audio_head*priv->audio_in.blocksize, len);
    priv->audio_head = (priv->audio_head+1) % priv->audio_buffer_size;
    priv->audio_cnt--;
    priv->audio_sent_blocks_total++;
    return (double)priv->audio_sent_blocks_total*priv->audio_secs_per_block;
}

static int get_audio_framesize(priv_t *priv)
{
    return(priv->audio_in.blocksize);
}

#endif /* USE_TV && HAVE_TV_V4L2 */