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fftools/ffmpeg: store a separate copy of input codec parameters 

Use it instead of AVStream.codecpar in the main thread. While
AVStream.codecpar is documented to only be updated when the stream is
added or avformat_find_stream_info(), it is actually updated during
demuxing. Accessing it from a different thread then constitutes a race.

Ideally, some mechanism should eventually be provided for signalling
parameter updates to the user. Then the demuxing thread could pick up
the changes and propagate them to the decoder.
This commit is contained in:
Anton Khirnov 2022-08-13 17:03:39 +02:00
parent 75ffca7eef
commit ab31473830
3 changed files with 31 additions and 20 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

39
fftools/ffmpeg.c
View File

@ -608,6 +608,7 @@ static void ffmpeg_cleanup(int ret)
av_freep(&ist->dts_buffer);
avcodec_free_context(&ist->dec_ctx);
avcodec_parameters_free(&ist->par);
av_freep(&input_streams[i]);
}
@ -1492,7 +1493,7 @@ static void print_final_stats(int64_t total_size)
for (j = 0; j < f->nb_streams; j++) {
InputStream *ist = input_streams[f->ist_index + j];
enum AVMediaType type = ist->st->codecpar->codec_type;
enum AVMediaType type = ist->par->codec_type;
total_size += ist->data_size;
total_packets += ist->nb_packets;
@ -1809,7 +1810,7 @@ static void flush_encoders(void)
for (x = 0; x < fg->nb_inputs; x++) {
InputFilter *ifilter = fg->inputs[x];
if (ifilter->format < 0 &&
ifilter_parameters_from_codecpar(ifilter, ifilter->ist->st->codecpar) < 0) {
ifilter_parameters_from_codecpar(ifilter, ifilter->ist->par) < 0) {
av_log(NULL, AV_LOG_ERROR, "Error copying paramerets from input stream\n");
exit_program(1);
}
@ -1912,11 +1913,11 @@ static void do_streamcopy(InputStream *ist, OutputStream *ost, const AVPacket *p
if (pkt->dts == AV_NOPTS_VALUE) {
opkt->dts = av_rescale_q(ist->dts, AV_TIME_BASE_Q, ost->mux_timebase);
} else if (ost->st->codecpar->codec_type == AVMEDIA_TYPE_AUDIO) {
int duration = av_get_audio_frame_duration2(ist->st->codecpar, pkt->size);
int duration = av_get_audio_frame_duration2(ist->par, pkt->size);
if(!duration)
duration = ist->st->codecpar->frame_size;
duration = ist->par->frame_size;
opkt->dts = av_rescale_delta(ist->st->time_base, pkt->dts,
(AVRational){1, ist->st->codecpar->sample_rate}, duration,
(AVRational){1, ist->par->sample_rate}, duration,
&ist->filter_in_rescale_delta_last, ost->mux_timebase);
/* dts will be set immediately afterwards to what pts is now */
opkt->pts = opkt->dts - ost_tb_start_time;
@ -1976,7 +1977,7 @@ static int ifilter_send_frame(InputFilter *ifilter, AVFrame *frame, int keep_ref
/* determine if the parameters for this input changed */
need_reinit = ifilter->format != frame->format;
switch (ifilter->ist->st->codecpar->codec_type) {
switch (ifilter->ist->par->codec_type) {
case AVMEDIA_TYPE_AUDIO:
need_reinit |= ifilter->sample_rate != frame->sample_rate ||
av_channel_layout_compare(&ifilter->ch_layout, &frame->ch_layout);
@ -2056,7 +2057,7 @@ static int ifilter_send_eof(InputFilter *ifilter, int64_t pts)
} else {
// the filtergraph was never configured
if (ifilter->format < 0) {
ret = ifilter_parameters_from_codecpar(ifilter, ifilter->ist->st->codecpar);
ret = ifilter_parameters_from_codecpar(ifilter, ifilter->ist->par);
if (ret < 0)
return ret;
}
@ -2212,9 +2213,9 @@ static int decode_video(InputStream *ist, AVPacket *pkt, int *got_output, int64_
// The following line may be required in some cases where there is no parser
// or the parser does not has_b_frames correctly
if (ist->st->codecpar->video_delay < ist->dec_ctx->has_b_frames) {
if (ist->par->video_delay < ist->dec_ctx->has_b_frames) {
if (ist->dec_ctx->codec_id == AV_CODEC_ID_H264) {
ist->st->codecpar->video_delay = ist->dec_ctx->has_b_frames;
ist->par->video_delay = ist->dec_ctx->has_b_frames;
} else
av_log(ist->dec_ctx, AV_LOG_WARNING,
"video_delay is larger in decoder than demuxer %d > %d.\n"
@ -2222,7 +2223,7 @@ static int decode_video(InputStream *ist, AVPacket *pkt, int *got_output, int64_
"of this file to https://streams.videolan.org/upload/ "
"and contact the ffmpeg-devel mailing list. (ffmpeg-devel@ffmpeg.org)\n",
ist->dec_ctx->has_b_frames,
ist->st->codecpar->video_delay);
ist->par->video_delay);
}
if (ret != AVERROR_EOF)
@ -2391,7 +2392,7 @@ static int send_filter_eof(InputStream *ist)
/* pkt = NULL means EOF (needed to flush decoder buffers) */
static int process_input_packet(InputStream *ist, const AVPacket *pkt, int no_eof)
{
const AVCodecParameters *par = ist->st->codecpar;
const AVCodecParameters *par = ist->par;
int ret = 0, i;
int repeating = 0;
int eof_reached = 0;
@ -2751,7 +2752,7 @@ static int init_output_stream_streamcopy(OutputStream *ost)
if (!codec_ctx)
return AVERROR(ENOMEM);
ret = avcodec_parameters_to_context(codec_ctx, ist->st->codecpar);
ret = avcodec_parameters_to_context(codec_ctx, ist->par);
if (ret >= 0)
ret = av_opt_set_dict(codec_ctx, &ost->encoder_opts);
if (ret < 0) {
@ -3120,8 +3121,8 @@ static int init_output_stream_encode(OutputStream *ost, AVFrame *frame)
case AVMEDIA_TYPE_SUBTITLE:
enc_ctx->time_base = AV_TIME_BASE_Q;
if (!enc_ctx->width) {
enc_ctx->width = input_streams[ost->source_index]->st->codecpar->width;
enc_ctx->height = input_streams[ost->source_index]->st->codecpar->height;
enc_ctx->width = input_streams[ost->source_index]->par->width;
enc_ctx->height = input_streams[ost->source_index]->par->height;
}
break;
case AVMEDIA_TYPE_DATA:
@ -3678,7 +3679,7 @@ static void decode_flush(InputFile *ifile)
if (ist->decoding_needed) {
/* report last frame duration to the demuxer thread */
if (ist->st->codecpar->codec_type == AVMEDIA_TYPE_AUDIO) {
if (ist->par->codec_type == AVMEDIA_TYPE_AUDIO) {
LastFrameDuration dur;
dur.stream_idx = i;
@ -3721,7 +3722,7 @@ static void ts_discontinuity_detect(InputFile *ifile, InputStream *ist,
"timestamp discontinuity for stream #%d:%d "
"(id=%d, type=%s): %"PRId64", new offset= %"PRId64"\n",
ist->file_index, ist->st->index, ist->st->id,
av_get_media_type_string(ist->st->codecpar->codec_type),
av_get_media_type_string(ist->par->codec_type),
delta, ifile->ts_offset_discont);
pkt->dts -= av_rescale_q(delta, AV_TIME_BASE_Q, ist->st->time_base);
if (pkt->pts != AV_NOPTS_VALUE)
@ -3772,8 +3773,8 @@ static void ts_discontinuity_process(InputFile *ifile, InputStream *ist,
pkt->pts += offset;
// detect timestamp discontinuities for audio/video
if ((ist->st->codecpar->codec_type == AVMEDIA_TYPE_VIDEO ||
ist->st->codecpar->codec_type == AVMEDIA_TYPE_AUDIO) &&
if ((ist->par->codec_type == AVMEDIA_TYPE_VIDEO ||
ist->par->codec_type == AVMEDIA_TYPE_AUDIO) &&
pkt->dts != AV_NOPTS_VALUE)
ts_discontinuity_detect(ifile, ist, pkt);
}
@ -3872,7 +3873,7 @@ static int process_input(int file_index)
if (debug_ts) {
av_log(NULL, AV_LOG_INFO, "demuxer+ffmpeg -> ist_index:%d type:%s pkt_pts:%s pkt_pts_time:%s pkt_dts:%s pkt_dts_time:%s duration:%s duration_time:%s off:%s off_time:%s\n",
ifile->ist_index + pkt->stream_index,
av_get_media_type_string(ist->st->codecpar->codec_type),
av_get_media_type_string(ist->par->codec_type),
av_ts2str(pkt->pts), av_ts2timestr(pkt->pts, &ist->st->time_base),
av_ts2str(pkt->dts), av_ts2timestr(pkt->dts, &ist->st->time_base),
av_ts2str(pkt->duration), av_ts2timestr(pkt->duration, &ist->st->time_base),

6
fftools/ffmpeg.h
View File

@ -323,6 +323,12 @@ typedef struct InputStream {
#define DECODING_FOR_FILTER 2
int processing_needed; /* non zero if the packets must be processed */
/**
* Codec parameters - to be used by the decoding/streamcopy code.
* st->codecpar should not be accessed, because it may be modified
* concurrently by the demuxing thread.
*/
AVCodecParameters *par;
AVCodecContext *dec_ctx;
const AVCodec *dec;
AVFrame *decoded_frame;

6
fftools/ffmpeg_opt.c
View File

@ -1090,7 +1090,11 @@ static void add_input_streams(OptionsContext *o, AVFormatContext *ic)
abort();
}
ret = avcodec_parameters_from_context(par, ist->dec_ctx);
ist->par = avcodec_parameters_alloc();
if (!ist->par)
exit_program(1);
ret = avcodec_parameters_from_context(ist->par, ist->dec_ctx);
if (ret < 0) {
av_log(NULL, AV_LOG_ERROR, "Error initializing the decoder context.\n");
exit_program(1);