mpv/common/recorder.c

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/*
* 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) {
2017-10-23 08:53:28 +00:00
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);
}