From ab3147383006f1a31978efce23c6bad38a754e05 Mon Sep 17 00:00:00 2001 From: Anton Khirnov Date: Sat, 13 Aug 2022 17:03:39 +0200 Subject: [PATCH] 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. --- 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@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);