path: root/plugins/vorbis/vorbis.c

/*
    DeaDBeeF -- the music player
    Copyright (C) 2009-2014 Alexey Yakovenko and other contributors

    This software is provided 'as-is', without any express or implied
    warranty.  In no event will the authors be held liable for any damages
    arising from the use of this software.

    Permission is granted to anyone to use this software for any purpose,
    including commercial applications, and to alter it and redistribute it
    freely, subject to the following restrictions:

    1. The origin of this software must not be misrepresented; you must not
     claim that you wrote the original software. If you use this software
     in a product, an acknowledgment in the product documentation would be
     appreciated but is not required.

    2. Altered source versions must be plainly marked as such, and must not be
     misrepresented as being the original software.

    3. This notice may not be removed or altered from any source distribution.
*/

#ifdef HAVE_CONFIG_H
#  include <config.h>
#endif
#include <vorbis/vorbisfile.h>
#include <string.h>
#include <stdlib.h>
#include <limits.h>
#include <unistd.h>
#include <math.h>
#include <stdbool.h>
#include "../../deadbeef.h"
#include "../liboggedit/oggedit.h"

#define min(x,y) ((x)<(y)?(x):(y))
#define max(x,y) ((x)>(y)?(x):(y))

// #define trace(...) { fprintf (stderr, __VA_ARGS__); }
#define trace(fmt,...)

#if WORDS_BIGENDIAN
#define CVORBIS_ENDIANNESS 1
#else
#define CVORBIS_ENDIANNESS 0
#endif

#define RG_REFERENCE_LOUDNESS -1
#define DELIMITER "\n - \n"

static DB_decoder_t plugin;
static DB_functions_t *deadbeef;

typedef struct {
    DB_fileinfo_t info;
    OggVorbis_File vorbis_file;
    int cur_bit_stream;
    float next_update;
    DB_playItem_t *it;
    const DB_playItem_t *new_track;
    uint8_t *channel_map;
} ogg_info_t;

static size_t
cvorbis_fread (void *ptr, size_t size, size_t nmemb, void *datasource) {
    size_t ret = deadbeef->fread (ptr, size, nmemb, datasource);
//    trace ("cvorbis_fread %d %d %d\n", size, nmemb, ret);
    return ret;
}

static int
cvorbis_fseek (void *datasource, ogg_int64_t offset, int whence) {
    DB_FILE *f = (DB_FILE *)datasource;
    return deadbeef->fseek (f, offset, whence);
}

static int
cvorbis_fclose (void *datasource) {
    deadbeef->fclose (datasource);
    return 0;
}

static long
cvorbis_ftell (void *datasource) {
    return deadbeef->ftell (datasource);
}

static const char
*gain_tag_name(const int tag_enum)
{
    switch(tag_enum) {
        case DDB_REPLAYGAIN_ALBUMGAIN:
            return "REPLAYGAIN_ALBUM_GAIN";
        case DDB_REPLAYGAIN_ALBUMPEAK:
            return "REPLAYGAIN_ALBUM_PEAK";
        case DDB_REPLAYGAIN_TRACKGAIN:
            return "REPLAYGAIN_TRACK_GAIN";
        case DDB_REPLAYGAIN_TRACKPEAK:
            return "REPLAYGAIN_TRACK_PEAK";
        case RG_REFERENCE_LOUDNESS:
            return "REPLAYGAIN_REFERENCE_LOUDNESS";
        default:
            return "";
    }
}

static bool
is_special_tag(const char *tag) {
    return !strcasecmp(tag, gain_tag_name(DDB_REPLAYGAIN_ALBUMGAIN)) ||
           !strcasecmp(tag, gain_tag_name(DDB_REPLAYGAIN_ALBUMPEAK)) ||
           !strcasecmp(tag, gain_tag_name(DDB_REPLAYGAIN_TRACKGAIN)) ||
           !strcasecmp(tag, gain_tag_name(DDB_REPLAYGAIN_TRACKPEAK)) ||
           !strcasecmp(tag, gain_tag_name(RG_REFERENCE_LOUDNESS));
}

static bool
add_meta(DB_playItem_t *it, const char *key, const char *value)
{
    const char *old_value = deadbeef->pl_find_meta(it, key);
    if (old_value) {
        char *new_value = malloc(strlen(old_value) + strlen(DELIMITER) + strlen(value) + 1);
        if (new_value) {
            sprintf(new_value, "%s"DELIMITER"%s", old_value, value);
            deadbeef->pl_replace_meta(it, key, new_value);
            free(new_value);
            return true;
        }
    }
    else {
        deadbeef->pl_add_meta(it, key, value);
        return true;
    }
}

static bool
replaygain_tag(DB_playItem_t *it, const int tag_enum, const char *tag, const char *value)
{
    if (strcasecmp(gain_tag_name(tag_enum), tag))
        return false;

    deadbeef->pl_set_item_replaygain (it, tag_enum, atof(value));
    return true;
}

static int
update_vorbis_comments (DB_playItem_t *it, OggVorbis_File *vorbis_file, const int tracknum) {
    const vorbis_comment *vc = ov_comment(vorbis_file, tracknum);
    if (!vc) {
        trace("update_vorbis_comments: ov_comment failed\n");
        return -1;
    }

    deadbeef->pl_delete_all_meta (it);
    for (int i = 0; i < vc->comments; i++) {
        char *tag = strdup(vc->user_comments[i]);
        char *value;
        if (tag && (value = strchr(tag, '='))) {
            *value++ = '\0';
            if (!replaygain_tag(it, DDB_REPLAYGAIN_ALBUMGAIN, tag, value) &&
                !replaygain_tag(it, DDB_REPLAYGAIN_ALBUMPEAK, tag, value) &&
                !replaygain_tag(it, DDB_REPLAYGAIN_TRACKGAIN, tag, value) &&
                !replaygain_tag(it, DDB_REPLAYGAIN_TRACKPEAK, tag, value)) {
                if (!strcasecmp(tag, gain_tag_name(RG_REFERENCE_LOUDNESS)))
                    deadbeef->pl_replace_meta(it, ":REPLAYGAIN_REFERENCE_LOUDNESS", value);
                else
                    add_meta(it, oggedit_map_tag(tag, "tag2meta"), value);
                }
            free(tag);
        }
    }

    deadbeef->pl_add_meta (it, "title", NULL);
    uint32_t f = deadbeef->pl_get_item_flags (it);
    f &= ~DDB_TAG_MASK;
    f |= DDB_TAG_VORBISCOMMENTS;
    deadbeef->pl_set_item_flags (it, f);
    ddb_playlist_t *plt = deadbeef->plt_get_curr ();
    if (plt) {
        deadbeef->plt_modified (plt);
        deadbeef->plt_unref (plt);
    }
    deadbeef->sendmessage (DB_EV_PLAYLISTCHANGED, 0, 0, 0);

    return 0;
}

static void
set_meta_ll(DB_playItem_t *it, const char *key, const int64_t value)
{
    char string[11];
    sprintf(string, "%lld", value);
    deadbeef->pl_replace_meta(it, key, string);
}

static int
cvorbis_seek_sample (DB_fileinfo_t *_info, int sample) {
    ogg_info_t *info = (ogg_info_t *)_info;
    if (sample < 0) {
        trace ("vorbis: negative seek sample - ignored, but it is a bug!\n");
        return -1;
    }
    if (!info->info.file) {
        trace ("vorbis: file is NULL on seek\n");
        return -1;
    }
    if (sample == 0) {
        deadbeef->pl_lock ();
        const char *filetype = deadbeef->pl_find_meta_raw(info->it, ":FILETYPE");
        if (filetype && strncmp(filetype, "Ogg Vorbis", 10)) {
            sample = 1; // workaround libvorbis bug #1486 (ddb issue #1116)
        }
        deadbeef->pl_unlock ();
    }
    sample += info->it->startsample;
    trace ("vorbis: seek to sample %d\n", sample);
    int res = ov_pcm_seek (&info->vorbis_file, sample);
    if (res != 0 && res != OV_ENOSEEK) {
        trace ("vorbis: error %x seeking to sample %d\n", res, sample);
        return -1;
    }
    int tell = ov_pcm_tell (&info->vorbis_file);
    if (tell != sample) {
        trace ("vorbis: failed to do sample-accurate seek (%d->%d)\n", sample, tell);
    }
    trace ("vorbis: seek successful\n")
    _info->readpos = (float)(sample - info->it->startsample)/_info->fmt.samplerate;
    info->next_update = -2;
    return 0;
}

static DB_fileinfo_t *
cvorbis_open (uint32_t hints) {
    return calloc(1, sizeof (ogg_info_t));
}

static int
cvorbis_init (DB_fileinfo_t *_info, DB_playItem_t *it) {
    trace("cvorbis_init\n");
    ogg_info_t *info = (ogg_info_t *)_info;
    info->new_track = info->it = it;
    deadbeef->pl_item_ref (it);
    deadbeef->pl_replace_meta (it, "!FILETYPE", "OggVorbis");

    deadbeef->pl_lock ();
    info->info.file = deadbeef->fopen (deadbeef->pl_find_meta (it, ":URI"));
    deadbeef->pl_unlock ();
    if (!info->info.file) {
        trace ("ogg: failed to open file %s\n", deadbeef->pl_find_meta (it, ":URI"));
        return -1;
    }
    if (info->info.file->vfs->is_streaming () && deadbeef->fgetlength (info->info.file) == -1) {
        ov_callbacks ovcb = {
            .read_func = cvorbis_fread,
            .seek_func = NULL,
            .close_func = cvorbis_fclose,
            .tell_func = NULL
        };

        trace ("calling ov_open_callbacks\n");
        int err = ov_open_callbacks (info->info.file, &info->vorbis_file, NULL, 0, ovcb);
        if (err != 0) {
            trace ("ov_open_callbacks returned %d\n", err);
            return -1;
        }
        ddb_playlist_t *plt = deadbeef->pl_get_playlist (it);
        deadbeef->plt_set_item_duration (plt, it, -1);
        if (plt) {
            deadbeef->plt_unref (plt);
        }
        deadbeef->pl_replace_meta (it, "!FILETYPE", "OggVorbis");
    }
    else
    {
        ov_callbacks ovcb = {
            .read_func = cvorbis_fread,
            .seek_func = cvorbis_fseek,
            .close_func = cvorbis_fclose,
            .tell_func = cvorbis_ftell
        };

        trace ("calling ov_open_callbacks\n");
        int err = ov_open_callbacks (info->info.file, &info->vorbis_file, NULL, 0, ovcb);
        if (err != 0) {
            trace ("ov_open_callbacks returned %d\n", err);
            return -1;
        }
    }
//    _info->readpos = 0;
    if (info->info.file->vfs->is_streaming ()) {
        info->it->startsample = 0;
        if (deadbeef->pl_get_item_duration (it) < 0) {
            it->endsample = -1;
        }
        else {
            it->endsample = ov_pcm_total (&info->vorbis_file, -1)-1;
        }
        if (update_vorbis_comments (it, &info->vorbis_file, -1))
            return -1;
        deadbeef->pl_set_meta_int(info->it, ":TRACKNUM", 0);
    }
    else {
        cvorbis_seek_sample (_info, 0);
    }

    vorbis_info *vi = ov_info (&info->vorbis_file, -1);
    if (!vi) {
        trace ("not a vorbis stream\n");
        return -1;
    }
    if (vi->rate <= 0) {
        trace ("vorbis: bad samplerate\n");
        return -1;
    }
    _info->plugin = &plugin;
    _info->fmt.bps = 16;
    _info->fmt.samplerate = vi->rate;
    _info->fmt.channels = vi->channels;
    info->channel_map = oggedit_vorbis_channel_map(vi->channels);
    for (int i = 0; i < _info->fmt.channels; i++) {
        _info->fmt.channelmask |= 1 << i;
    }

    return 0;
}

static void
cvorbis_free (DB_fileinfo_t *_info) {
    trace("cvorbis_free\n");
    ogg_info_t *info = (ogg_info_t *)_info;
    if (info) {
        if (info->it) {
            deadbeef->pl_item_unref (info->it);
        }
        free(info->channel_map);
        info->channel_map = NULL;
        if (info->info.file) {
            if (info->vorbis_file.datasource) {
                ov_clear (&info->vorbis_file);
            }
            else {
                deadbeef->fclose (info->info.file);
            }
        }
        free (info);
    }
}

static void send_event(DB_playItem_t *it, const int event_enum)
{
    ddb_event_track_t *event = (ddb_event_track_t *)deadbeef->event_alloc(event_enum);
    if (event->track = it)
        deadbeef->pl_item_ref(event->track);
    deadbeef->event_send((ddb_event_t *)event, 0, 0);
}

static bool
new_streaming_link(ogg_info_t *info, const int new_link)
{
    if (info->cur_bit_stream == 0 && new_link != 1)
        return false;

    trace("Streaming link changed from %d to %d\n", info->cur_bit_stream, new_link);
    deadbeef->pl_set_meta_int(info->it, ":TRACKNUM", new_link);
    update_vorbis_comments(info->it, &info->vorbis_file, new_link);
    send_event(info->it, DB_EV_SONGSTARTED);
    send_event(info->it, DB_EV_TRACKINFOCHANGED);
    deadbeef->sendmessage(DB_EV_PLAYLISTCHANGED, 0, 0, 0);
    info->cur_bit_stream = new_link;

    vorbis_info *vi = ov_info (&info->vorbis_file, new_link);
    if (vi && info->info.fmt.channels != vi->channels || info->info.fmt.samplerate != vi->rate) {
        // Streamer can't do this, so re-init the stream
        trace("Stream channel count changed from %d to %d\n", info->info.fmt.channels, vi->channels);
        trace("Stream channel count changed from %d to %d\n", info->info.fmt.samplerate, vi->rate);
        deadbeef->sendmessage(DB_EV_PAUSE, 0, 0, 0);
        deadbeef->sendmessage(DB_EV_TOGGLE_PAUSE, 0, 0, 0);
        return true;
    }

    return false;
}

static void
map_channels(int16_t *dest, const int16_t *src, const int16_t *src_end, const uint8_t *map, const int channel_count)
{
    while (src < src_end) {
        for (uint8_t *map_ptr = (uint8_t *)map; map_ptr < map + channel_count; map_ptr++, src++)
            dest[*map_ptr] = *src;
        dest += channel_count;
    }
}

static bool
is_playing_track(const DB_playItem_t *it)
{
    DB_playItem_t *track = deadbeef->streamer_get_playing_track();
    if (track)
        deadbeef->pl_item_unref(track);
    return track == it;
}

static int
cvorbis_read (DB_fileinfo_t *_info, char *buffer, int bytes_to_read) {
    ogg_info_t *info = (ogg_info_t *)_info;

    /* Work round some streamer limitations and infobar issue #22 */
    if (info->new_track && is_playing_track(info->new_track)) {
        info->new_track = NULL;
        send_event(info->it, DB_EV_TRACKINFOCHANGED);
        info->next_update = -2;
    }

    /* Don't read past the end of a sub-track */
    if (deadbeef->pl_get_item_flags(info->it) & DDB_IS_SUBTRACK) {
        const ogg_int64_t bytes_left = (info->it->endsample - ov_pcm_tell(&info->vorbis_file)) * 2 * _info->fmt.channels;
        if (bytes_left < bytes_to_read)
            bytes_to_read = bytes_left;
    }

    /* Read until we have enough bytes to satisfy streamer, or there are none left */
    char map_buffer[info->channel_map ? bytes_to_read : 0];
    char *ptr = info->channel_map ? map_buffer : buffer;
    int ret = OV_HOLE;
    int bytes_read = 0;
    while ((ret > 0 || ret == OV_HOLE) && bytes_read < bytes_to_read)
    {
        int new_link = -1;
        ret=ov_read (&info->vorbis_file, ptr+bytes_read, bytes_to_read-bytes_read, CVORBIS_ENDIANNESS, 2, 1, &new_link);

        if (ret < 0) {
            trace("cvorbis_read: ov_read returned %d\n", ret);
        }
        else if (new_link != info->cur_bit_stream && !ov_seekable(&info->vorbis_file) && new_streaming_link(info, new_link)) {
            bytes_read = bytes_to_read;
        }
        else {
            bytes_read += ret;
        }

//        trace("cvorbis_read got %d bytes towards %d bytes (%d bytes still required)\n", ret, bytes_to_read, bytes_to_read-bytes_read);
    }

    if (info->channel_map)
        map_channels((int16_t *)buffer, (int16_t *)map_buffer, (int16_t *)(ptr+bytes_read), info->channel_map, _info->fmt.channels);

    _info->readpos = (float)(ov_pcm_tell(&info->vorbis_file) - info->it->startsample) / _info->fmt.samplerate;
    if (_info->readpos > info->next_update) {
        const int rate = ov_bitrate_instant(&info->vorbis_file) / 1000;
        if (rate > 0) {
            deadbeef->streamer_set_bitrate(rate);
            info->next_update = info->next_update <= 0 ? info->next_update + 1 : _info->readpos + 5;
        }
    }
//    trace("cvorbis_read returning %d bytes out of %d\n", bytes_read, bytes_to_read);
    return bytes_read;
}

static int
cvorbis_seek (DB_fileinfo_t *_info, float time) {
    ogg_info_t *info = (ogg_info_t *)_info;
    return cvorbis_seek_sample (_info, time * info->info.fmt.samplerate);
}

static off_t sample_offset(OggVorbis_File *vorbis_file, const ogg_int64_t sample)
{
    if (sample <= 0 || sample == ov_pcm_total(vorbis_file, -1))
        return 0;

    if (ov_pcm_seek(vorbis_file, sample)) {
        trace("ov_pcm_seek failed to find sample %lld: %d\n", sample, ov_pcm_seek(vorbis_file, sample));
        return -1;
    }

    return ov_raw_tell(vorbis_file);
}

static DB_playItem_t *
cvorbis_insert (ddb_playlist_t *plt, DB_playItem_t *after, const char *fname) {
    DB_FILE *fp = deadbeef->fopen (fname);
    if (!fp) {
        trace ("vorbis: failed to fopen %s\n", fname);
        return NULL;
    }
    int64_t fsize = deadbeef->fgetlength (fp);
    if (fp->vfs->is_streaming ()) {
        DB_playItem_t *it = deadbeef->pl_item_alloc_init (fname, plugin.plugin.id);
        deadbeef->plt_set_item_duration (plt, it, -1);
        deadbeef->pl_add_meta (it, "title", NULL);
        after = deadbeef->plt_insert_item (plt, after, it);
        deadbeef->pl_item_unref (it);
        deadbeef->fclose (fp);
        return after;
    }
    ov_callbacks ovcb = {
        .read_func = cvorbis_fread,
        .seek_func = cvorbis_fseek,
        .close_func = cvorbis_fclose,
        .tell_func = cvorbis_ftell
    };
    OggVorbis_File vorbis_file;
    int err = ov_open_callbacks (fp, &vorbis_file, NULL, 0, ovcb);
    if (err != 0) {
        trace ("ov_open_callbacks returned %d\n", err);
        ov_clear (&vorbis_file);
        deadbeef->fclose (fp);
        return NULL;
    }

    long nstreams = ov_streams (&vorbis_file);
    int currentsample = 0;
    for (int stream = 0; stream < nstreams; stream++) {
        const vorbis_info *vi = ov_info (&vorbis_file, stream);
        if (!vi) {
            trace ("vorbis: ov_info failed for file %s stream %d\n", fname, stream);
            continue;
        }
        float duration = ov_time_total (&vorbis_file, stream);
        int totalsamples = ov_pcm_total (&vorbis_file, stream);

        DB_playItem_t *it = deadbeef->pl_item_alloc_init (fname, plugin.plugin.id);
        deadbeef->pl_set_meta_int (it, ":TRACKNUM", stream);
        deadbeef->plt_set_item_duration (plt, it, duration);
        if (nstreams > 1) {
            it->startsample = currentsample;
            it->endsample = currentsample + totalsamples - 1;
            deadbeef->pl_set_item_flags (it, DDB_IS_SUBTRACK);
        }

        if (update_vorbis_comments (it, &vorbis_file, stream))
            continue;
        int samplerate = vi->rate;

        const off_t start_offset = sample_offset(&vorbis_file, it->startsample-1);
        const off_t end_offset = sample_offset(&vorbis_file, it->endsample);
        char *filetype = NULL;
        const off_t stream_size = oggedit_vorbis_stream_info(deadbeef->fopen(fname), start_offset, end_offset, &filetype);
        if (filetype) {
            deadbeef->pl_replace_meta(it, ":FILETYPE", filetype);
            free(filetype);
        }
        if (stream_size > 0) {
            set_meta_ll(it, ":STREAM SIZE", stream_size);
            deadbeef->pl_set_meta_int(it, ":BITRATE", 8.f * samplerate * stream_size / totalsamples / 1000);
        }
        set_meta_ll (it, ":FILE_SIZE", fsize);
        deadbeef->pl_add_meta (it, ":BPS", "16");
        deadbeef->pl_set_meta_int (it, ":CHANNELS", vi->channels);
        deadbeef->pl_set_meta_int (it, ":SAMPLERATE", samplerate);
//        deadbeef->pl_set_meta_int (it, ":BITRATE", ov_bitrate (&vorbis_file, stream)/1000);

        if (nstreams == 1) {
            DB_playItem_t *cue = deadbeef->plt_insert_cue (plt, after, it, totalsamples, samplerate);
            if (cue) {
                deadbeef->pl_item_unref (it);
                deadbeef->pl_item_unref (cue);
                ov_clear (&vorbis_file);
                return cue;
            }

            deadbeef->pl_lock ();
            const char *cuesheet_meta = deadbeef->pl_find_meta (it, "cuesheet");
            if (cuesheet_meta) {
                trace("Embedded cuesheet found for %s\n", fname);
                const char *last_sheet = strstr(cuesheet_meta, DELIMITER);
                const char *cuesheet = last_sheet ? last_sheet + strlen(DELIMITER) : cuesheet_meta;
                cue = deadbeef->plt_insert_cue_from_buffer (plt, after, it, cuesheet, strlen (cuesheet), totalsamples, samplerate);
                if (cue) {
                    deadbeef->pl_unlock ();
                    deadbeef->pl_item_unref (it);
                    deadbeef->pl_item_unref (cue);
                    ov_clear (&vorbis_file);
                    return cue;
                }
            }
            deadbeef->pl_unlock ();
        }
        else {
            currentsample += totalsamples;
        }

        after = deadbeef->plt_insert_item (plt, after, it);
        deadbeef->pl_item_unref (it);
    }
    ov_clear (&vorbis_file);
    return after;
}

static int
vorbis_start (void) {
    return 0;
}

static int
vorbis_stop (void) {
    return 0;
}
int
cvorbis_read_metadata (DB_playItem_t *it) {
    DB_FILE *fp = NULL;
    OggVorbis_File vorbis_file;
    vorbis_info *vi = NULL;

    deadbeef->pl_lock ();
    fp = deadbeef->fopen (deadbeef->pl_find_meta (it, ":URI"));
    deadbeef->pl_unlock ();
    if (!fp) {
        trace ("cvorbis_read_metadata: failed to fopen %s\n", deadbeef->pl_find_meta (it, ":URI"));
        return -1;
    }
    if (fp->vfs->is_streaming ()) {
        trace ("cvorbis_read_metadata: failed to fopen %s\n", deadbeef->pl_find_meta (it, ":URI"));
        return -1;
    }
    ov_callbacks ovcb = {
        .read_func = cvorbis_fread,
        .seek_func = cvorbis_fseek,
        .close_func = cvorbis_fclose,
        .tell_func = cvorbis_ftell
    };
    int res = ov_open_callbacks (fp, &vorbis_file, NULL, 0, ovcb);
    if (res != 0) {
        trace ("cvorbis_read_metadata: ov_open_callbacks returned %d\n", res);
        return -1;
    }
    int tracknum = deadbeef->pl_find_meta_int (it, ":TRACKNUM", -1);
    vi = ov_info (&vorbis_file, tracknum);
    if (!vi) {
        trace ("cvorbis_read_metadata: failed to ov_open %s\n", deadbeef->pl_find_meta (it, ":URI"));
        ov_clear (&vorbis_file);
        return -1;
    }

    if (update_vorbis_comments (it, &vorbis_file, tracknum)) {
        ov_clear (&vorbis_file);
        return -1;
    }

    ov_clear (&vorbis_file);
    return 0;
}

static void
split_tag(vorbis_comment *tags, const char *key, const char *value)
{
    if (key && value) {
        const char *p;
        while (p = strstr(value, DELIMITER)) {
            char v[p - value + 1];
            strncpy(v, value, p-value);
            v[p-value] = 0;
            vorbis_comment_add_tag(tags, key, v);
            value = p + strlen(DELIMITER);
        }

        vorbis_comment_add_tag(tags, key, value);
    }
}

static void
merge_gain_tag(DB_playItem_t *it, vorbis_comment *vc, vorbis_comment *tags, const int tag_enum, const char *pattern, const int min, const int max)
{
    const char *key = gain_tag_name(tag_enum);

    char *end;
    const char *meta_value = deadbeef->pl_find_meta(it, key);
    const float value = meta_value ? strtof(meta_value, &end) : 0;
    if (meta_value && end != meta_value && value > min && value < max) {
        char tag_value[10];
        sprintf(tag_value, pattern, value);
        vorbis_comment_add_tag(tags, key, tag_value);
    }
    else {
        const char *tag_value = vorbis_comment_query(vc, key, 0);
        if (tag_value)
             vorbis_comment_add_tag(tags, key, tag_value);
    }
}

static vorbis_comment
*tags_list(DB_playItem_t *it, OggVorbis_File *vorbis_file)
{
    vorbis_comment *vc = ov_comment (vorbis_file, -1);
    if (!vc)
        return NULL;

    vorbis_comment *tags = calloc(1, sizeof(vorbis_comment));
    if (!tags)
        return NULL;

    deadbeef->pl_lock ();
    merge_gain_tag(it, vc, tags, DDB_REPLAYGAIN_ALBUMGAIN, "%0.2f dB", -100, 100);
    merge_gain_tag(it, vc, tags, DDB_REPLAYGAIN_ALBUMPEAK, "%0.8f", 0, 2);
    merge_gain_tag(it, vc, tags, DDB_REPLAYGAIN_TRACKGAIN, "%0.2f dB", -100, 100);
    merge_gain_tag(it, vc, tags, DDB_REPLAYGAIN_TRACKPEAK, "%0.8f", 0, 2);
    merge_gain_tag(it, vc, tags, RG_REFERENCE_LOUDNESS, "%0.1f dB", 0, 128);
    for (DB_metaInfo_t *m = deadbeef->pl_get_metadata_head(it); m; m = m->next) {
        char *key = strdup(m->key);
        if (key && key[0] != ':' && key[0] != '!' && !is_special_tag(key)) {
            split_tag(tags, oggedit_map_tag(key, "meta2tag"), m->value);
            free(key);
        }
    }
    deadbeef->pl_unlock ();

    return tags;
}

static int
cvorbis_write_metadata (DB_playItem_t *it) {
    char fname[PATH_MAX];
    deadbeef->pl_get_meta (it, ":URI", fname, sizeof (fname));

    DB_FILE *fp = deadbeef->fopen (fname);
    if (!fp) {
        trace ("cvorbis_write_metadata: failed to fopen %s\n", fname);
        return -1;
    }
    ov_callbacks ovcb = {
        .read_func = cvorbis_fread,
        .seek_func = cvorbis_fseek,
        .close_func = cvorbis_fclose,
        .tell_func = cvorbis_ftell
    };
    OggVorbis_File vorbis_file;
    int err = ov_test_callbacks (fp, &vorbis_file, NULL, 0, ovcb);
    if (err != 0) {
        trace ("ov_test_callbacks returned %d\n", err);
        deadbeef->fclose (fp);
        return -1;
    }

    vorbis_comment *tags = tags_list(it, &vorbis_file);
    ov_clear(&vorbis_file);
    if (!tags) {
        trace("cvorbis_write_metadata: tags list allocation failed\n");
        return -1;
    }

    deadbeef->pl_lock();
    const char *stream_size_string = deadbeef->pl_find_meta(it, ":STREAM SIZE");
    const size_t stream_size = stream_size_string ? (off_t)atoll(stream_size_string) : 0;
    deadbeef->pl_unlock();
    const off_t file_size = oggedit_write_vorbis_metadata (deadbeef->fopen(fname), fname, 0, stream_size, tags->comments, tags->user_comments);
    vorbis_comment_clear(tags);
    free(tags);
    if (file_size <= 0) {
        trace ("cvorbis_write_metadata: failed to write tags to %s, code %d\n", fname, file_size);
        return -1;
    }

    set_meta_ll(it, ":FILE_SIZE", (int64_t)file_size);
    return cvorbis_read_metadata(it);
}


static const char * exts[] = { "ogg", "ogx", "oga", NULL };

// define plugin interface
static DB_decoder_t plugin = {
    .plugin.api_vmajor = 1,
    .plugin.api_vminor = 0,
    .plugin.version_major = 1,
    .plugin.version_minor = 0,
    .plugin.type = DB_PLUGIN_DECODER,
    .plugin.id = "stdogg",
    .plugin.name = "OggVorbis decoder",
    .plugin.descr = "OggVorbis decoder using standard xiph.org libraries",
    .plugin.copyright =
    "OggVorbis plugin for DeaDBeeF\n"
    "Copyright (C) 2009-2014 Alexey Yakovenko et al.\n"
    "\n"
    "vcedit.c\n"
    "Ogg Vorbis plugin Ogg edit functions\n"
    "\n"
    "Copyright (C) 2014 Ian Nartowicz <deadbeef@nartowicz.co.uk>\n"
    "This software is provided 'as-is', without any express or implied\n"
    "warranty.  In no event will the authors be held liable for any damages\n"
    "arising from the use of this software.\n"
    "\n"
    "Permission is granted to anyone to use this software for any purpose,\n"
    "including commercial applications, and to alter it and redistribute it\n"
    "freely, subject to the following restrictions:\n"
    "\n"
    "1. The origin of this software must not be misrepresented; you must not\n"
    " claim that you wrote the original software. If you use this software\n"
    " in a product, an acknowledgment in the product documentation would be\n"
    " appreciated but is not required.\n"
    "\n"
    "2. Altered source versions must be plainly marked as such, and must not be\n"
    " misrepresented as being the original software.\n"
    "\n"
    "3. This notice may not be removed or altered from any source distribution.\n"
    "\n"
    "\n"
    "\n"
    "Uses libogg,libvorbis Copyright (c) 2002, Xiph.org Foundation\n"
    "\n"
    "Redistribution and use in source and binary forms, with or without\n"
    "modification, are permitted provided that the following conditions\n"
    "are met:\n"
    "\n"
    "- Redistributions of source code must retain the above copyright\n"
    "notice, this list of conditions and the following disclaimer.\n"
    "\n"
    "- Redistributions in binary form must reproduce the above copyright\n"
    "notice, this list of conditions and the following disclaimer in the\n"
    "documentation and/or other materials provided with the distribution.\n"
    "\n"
    "- Neither the name of the DeaDBeeF Player nor the names of its\n"
    "contributors may be used to endorse or promote products derived from\n"
    "this software without specific prior written permission.\n"
    "\n"
    "THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS\n"
    "``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT\n"
    "LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR\n"
    "A PARTICULAR PURPOSE ARE DISCLAIMED.  IN NO EVENT SHALL THE FOUNDATION OR\n"
    "CONTRIBUTORS BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL,\n"
    "EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO,\n"
    "PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR\n"
    "PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF\n"
    "LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING\n"
    "NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS\n"
    "SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.\n"
    ,
    .plugin.website = "http://deadbeef.sf.net",
    .plugin.start = vorbis_start,
    .plugin.stop = vorbis_stop,
    .open = cvorbis_open,
    .init = cvorbis_init,
    .free = cvorbis_free,
    .read = cvorbis_read,
    // vorbisfile can't output float32
//    .read_float32 = cvorbis_read_float32,
    .seek = cvorbis_seek,
    .seek_sample = cvorbis_seek_sample,
    .insert = cvorbis_insert,
    .read_metadata = cvorbis_read_metadata,
    .write_metadata = cvorbis_write_metadata,
    .exts = exts
};

DB_plugin_t *
vorbis_load (DB_functions_t *api) {
    deadbeef = api;
    return DB_PLUGIN (&plugin);
}