[FFmpeg-devel] [PATCH] fftools/ffmpeg: store a separate copy of input codec parameters
Anton Khirnov
anton at khirnov.net
Sat Aug 13 18:36:01 EEST 2022
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.
---
fftools/ffmpeg.c | 39 ++++++++++++++++++++-------------------
fftools/ffmpeg.h | 6 ++++++
fftools/ffmpeg_opt.c | 6 +++++-
3 files changed, 31 insertions(+), 20 deletions(-)
diff --git a/fftools/ffmpeg.c b/fftools/ffmpeg.c
index 8eb7759392..ef7177fc33 100644
--- a/fftools/ffmpeg.c
+++ b/fftools/ffmpeg.c
@@ -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 at 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),
diff --git a/fftools/ffmpeg.h b/fftools/ffmpeg.h
index 6991ba7632..44cc23fa84 100644
--- a/fftools/ffmpeg.h
+++ b/fftools/ffmpeg.h
@@ -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;
diff --git a/fftools/ffmpeg_opt.c b/fftools/ffmpeg_opt.c
index 97f14b2a5b..30ca5cd609 100644
--- a/fftools/ffmpeg_opt.c
+++ b/fftools/ffmpeg_opt.c
@@ -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);
--
2.35.1
More information about the ffmpeg-devel
mailing list