aboutsummaryrefslogtreecommitdiffhomepage
path: root/common/recorder.c
blob: 9970c05c3226b9a2f8aabc5e36e78deb9fbafe6d (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
/*
 * This file is part of mpv.
 *
 * mpv is free software; you can redistribute it and/or
 * modify it under the terms of the GNU Lesser General Public
 * License as published by the Free Software Foundation; either
 * version 2.1 of the License, or (at your option) any later version.
 *
 * mpv is distributed in the hope that it will be useful,
 * but WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 * GNU Lesser General Public License for more details.
 *
 * You should have received a copy of the GNU Lesser General Public
 * License along with mpv.  If not, see <http://www.gnu.org/licenses/>.
 */

#include <math.h>

#include <libavformat/avformat.h>

#include "common/av_common.h"
#include "common/common.h"
#include "common/global.h"
#include "common/msg.h"
#include "demux/packet.h"
#include "demux/stheader.h"

#include "recorder.h"

#define PTS_ADD(a, b) ((a) == MP_NOPTS_VALUE ? (a) : ((a) + (b)))

// Maximum number of packets we buffer at most to attempt to resync streams.
// Essentially, this should be higher than the highest supported keyframe
// interval.
#define QUEUE_MAX_PACKETS 256
// Number of packets we should buffer at least to determine timestamps (due to
// codec delay and frame reordering, and potentially lack of DTS).
// Keyframe flags can trigger this earlier.
#define QUEUE_MIN_PACKETS 16

struct mp_recorder {
    struct mpv_global *global;
    struct mp_log *log;

    struct mp_recorder_sink **streams;
    int num_streams;

    bool opened;            // mux context is valid
    bool muxing;            // we're currently recording (instead of preparing)
    bool muxing_from_start; // no discontinuity at start
    bool dts_warning;

    // The start timestamp of the currently recorded segment (the timestamp of
    // the first packet of the incoming packet stream).
    double base_ts;
    // The output packet timestamp corresponding to base_ts. It's the timestamp
    // of the first packet of the current segment written to the output.
    double rebase_ts;

    AVFormatContext *mux;
};

struct mp_recorder_sink {
    struct mp_recorder *owner;
    struct sh_stream *sh;
    AVStream *av_stream;
    double max_out_pts;
    bool discont;
    bool proper_eof;
    struct demux_packet **packets;
    int num_packets;
};

static int add_stream(struct mp_recorder *priv, struct sh_stream *sh)
{
    enum AVMediaType av_type = mp_to_av_stream_type(sh->type);
    if (av_type == AVMEDIA_TYPE_UNKNOWN)
        return -1;

    struct mp_recorder_sink *rst = talloc(priv, struct mp_recorder_sink);
    *rst = (struct mp_recorder_sink) {
        .owner = priv,
        .sh = sh,
        .av_stream = avformat_new_stream(priv->mux, NULL),
        .max_out_pts = MP_NOPTS_VALUE,
    };

    if (!rst->av_stream)
        return -1;

    AVCodecParameters *avp = mp_codec_params_to_av(sh->codec);
    if (!avp)
        return -1;

#if LIBAVCODEC_VERSION_MICRO >= 100
    // We don't know the delay, so make something up. If the format requires
    // DTS, the result will probably be broken. FFmpeg provides nothing better
    // yet (unless you demux with libavformat, which contains tons of hacks
    // that try to determine a PTS).
    if (!sh->codec->lav_codecpar)
        avp->video_delay = 16;
#endif

    if (avp->codec_id == AV_CODEC_ID_NONE)
        return -1;

    if (avcodec_parameters_copy(rst->av_stream->codecpar, avp) < 0)
        return -1;

    rst->av_stream->time_base = mp_get_codec_timebase(sh->codec);

    MP_TARRAY_APPEND(priv, priv->streams, priv->num_streams, rst);
    return 0;
}

struct mp_recorder *mp_recorder_create(struct mpv_global *global,
                                       const char *target_file,
                                       struct sh_stream **streams,
                                       int num_streams)
{
    struct mp_recorder *priv = talloc_zero(NULL, struct mp_recorder);

    priv->global = global;
    priv->log = mp_log_new(priv, global->log, "recorder");

    if (!num_streams) {
        MP_ERR(priv, "No streams.\n");
        goto error;
    }

    priv->mux = avformat_alloc_context();
    if (!priv->mux)
        goto error;

    priv->mux->oformat = av_guess_format(NULL, target_file, NULL);
    if (!priv->mux->oformat) {
        MP_ERR(priv, "Output format not found.\n");
        goto error;
    }

    if (avio_open2(&priv->mux->pb, target_file, AVIO_FLAG_WRITE, NULL, NULL) < 0) {
        MP_ERR(priv, "Failed opening output file.\n");
        goto error;
    }

    for (int n = 0; n < num_streams; n++) {
        if (add_stream(priv, streams[n]) < 0) {
            MP_ERR(priv, "Can't mux one of the input streams.\n");
            goto error;
        }
    }

    // Not sure how to write this in a "standard" way. It appears only mkv
    // and mp4 support this directly.
    char version[200];
    snprintf(version, sizeof(version), "%s experimental stream recording "
             "feature (can generate broken files - please report bugs)",
             mpv_version);
    av_dict_set(&priv->mux->metadata, "encoding_tool", version, 0);

    if (avformat_write_header(priv->mux, NULL) < 0) {
        MP_ERR(priv, "Writing header failed.\n");
        goto error;
    }

    priv->opened = true;
    priv->muxing_from_start = true;

    priv->base_ts = MP_NOPTS_VALUE;
    priv->rebase_ts = 0;

    MP_WARN(priv, "This is an experimental feature. Output files might be "
                  "broken or not play correctly with various players "
                  "(including mpv itself).\n");

    return priv;

error:
    mp_recorder_destroy(priv);
    return NULL;
}

static void flush_packets(struct mp_recorder *priv)
{
    for (int n = 0; n < priv->num_streams; n++) {
        struct mp_recorder_sink *rst = priv->streams[n];
        for (int i = 0; i < rst->num_packets; i++)
            talloc_free(rst->packets[i]);
        rst->num_packets = 0;
    }
}

static void mux_packet(struct mp_recorder_sink *rst,
                       struct demux_packet *pkt)
{
    struct mp_recorder *priv = rst->owner;
    struct demux_packet mpkt = *pkt;

    double diff = priv->rebase_ts - priv->base_ts;
    mpkt.pts = PTS_ADD(mpkt.pts, diff);
    mpkt.dts = PTS_ADD(mpkt.dts, diff);

    rst->max_out_pts = MPMAX(rst->max_out_pts, pkt->pts);

    AVPacket avpkt;
    mp_set_av_packet(&avpkt, &mpkt, &rst->av_stream->time_base);

    avpkt.stream_index = rst->av_stream->index;

    if (avpkt.duration < 0 && rst->sh->type != STREAM_SUB)
        avpkt.duration = 0;

    AVPacket *new_packet = av_packet_clone(&avpkt);
    if (!new_packet) {
        MP_ERR(priv, "Failed to allocate packet.\n");
        return;
    }

    if (av_interleaved_write_frame(priv->mux, new_packet) < 0)
        MP_ERR(priv, "Failed writing packet.\n");
}

// Write all packets that currently can be written.
static void mux_packets(struct mp_recorder_sink *rst, bool force)
{
    struct mp_recorder *priv = rst->owner;
    if (!priv->muxing || !rst->num_packets)
        return;

    int safe_count = 0;
    for (int n = 0; n < rst->num_packets; n++) {
        if (rst->packets[n]->keyframe)
            safe_count = n;
    }
    if (force)
        safe_count = rst->num_packets;

    for (int n = 0; n < safe_count; n++) {
        mux_packet(rst, rst->packets[n]);
        talloc_free(rst->packets[n]);
    }

    // Remove packets[0..safe_count]
    memmove(&rst->packets[0], &rst->packets[safe_count],
            (rst->num_packets - safe_count) * sizeof(rst->packets[0]));
    rst->num_packets -= safe_count;
}

// If there was a discontinuity, check whether we can resume muxing (and from
// where).
static void check_restart(struct mp_recorder *priv)
{
    if (priv->muxing)
        return;

    double min_ts = INFINITY;
    double rebase_ts = 0;
    for (int n = 0; n < priv->num_streams; n++) {
        struct mp_recorder_sink *rst = priv->streams[n];
        int min_packets = rst->sh->type == STREAM_VIDEO ? QUEUE_MIN_PACKETS : 1;

        rebase_ts = MPMAX(rebase_ts, rst->max_out_pts);

        if (rst->num_packets < min_packets) {
            if (!rst->proper_eof && rst->sh->type != STREAM_SUB)
                return;
            continue;
        }

        for (int i = 0; i < min_packets; i++)
            min_ts = MPMIN(min_ts, rst->packets[i]->pts);
    }

    // Subtitle only stream (wait longer) or stream without any PTS (fuck it).
    if (!isfinite(min_ts))
        return;

    priv->rebase_ts = rebase_ts;
    priv->base_ts = min_ts;

    for (int n = 0; n < priv->num_streams; n++) {
        struct mp_recorder_sink *rst = priv->streams[n];
        rst->max_out_pts = min_ts;
    }

    priv->muxing = true;

    if (!priv->muxing_from_start)
        MP_WARN(priv, "Discontinuity at timestamp %f.\n", priv->rebase_ts);
}

void mp_recorder_destroy(struct mp_recorder *priv)
{
    if (priv->opened) {
        for (int n = 0; n < priv->num_streams; n++) {
            struct mp_recorder_sink *rst = priv->streams[n];
            if (!rst->proper_eof)
                continue;
            mux_packets(rst, true);
        }

        if (av_write_trailer(priv->mux) < 0)
            MP_ERR(priv, "Writing trailer failed.\n");
    }

    if (priv->mux) {
        if (avio_closep(&priv->mux->pb) < 0)
            MP_ERR(priv, "Closing file failed\n");

        avformat_free_context(priv->mux);
    }

    flush_packets(priv);
    talloc_free(priv);
}

// This is called on a seek, or when recording was started mid-stream.
void mp_recorder_mark_discontinuity(struct mp_recorder *priv)
{
    flush_packets(priv);

    for (int n = 0; n < priv->num_streams; n++) {
        struct mp_recorder_sink *rst = priv->streams[n];
        rst->discont = true;
        rst->proper_eof = false;
    }

    priv->muxing = false;
    priv->muxing_from_start = false;
}

// Get a stream for writing. The pointer is valid until mp_recorder is
// destroyed. The stream is the index referencing the stream passed to
// mp_recorder_create().
struct mp_recorder_sink *mp_recorder_get_sink(struct mp_recorder *r, int stream)
{
    assert(stream >= 0 && stream < r->num_streams);
    return r->streams[stream];
}

// Pass a packet to the given stream. The function does not own the packet, but
// can create a new reference to it if it needs to retain it. Can be NULL to
// signal proper end of stream.
void mp_recorder_feed_packet(struct mp_recorder_sink *rst,
                             struct demux_packet *pkt)
{
    struct mp_recorder *priv = rst->owner;

    if (!pkt) {
        rst->proper_eof = true;
        check_restart(priv);
        mux_packets(rst, false);
        return;
    }

    if (pkt->dts == MP_NOPTS_VALUE && !priv->dts_warning) {
        // No, FFmpeg has no actually usable helpers to generate correct DTS.
        // No, FFmpeg doesn't tell us which formats need DTS at all.
        // No, we can not shut up the FFmpeg warning, which will follow.
        MP_WARN(priv, "Source stream misses DTS on at least some packets!\n"
                      "If the target file format requires DTS, the written\n"
                      "file will be invalid.\n");
        priv->dts_warning = true;
    }

    if (rst->discont && !pkt->keyframe)
        return;
    rst->discont = false;

    if (rst->num_packets >= QUEUE_MAX_PACKETS) {
        MP_ERR(priv, "Stream %d has too many queued packets; dropping.\n",
               rst->av_stream->index);
        return;
    }

    pkt = demux_copy_packet(pkt);
    if (!pkt)
        return;
    MP_TARRAY_APPEND(rst, rst->packets, rst->num_packets, pkt);

    check_restart(priv);
    mux_packets(rst, false);
}