[FFmpeg-devel] [PATCH] ffmpeg: fix implementation of updated input start time
Gyan Doshi
ffmpeg at gyani.pro
Sun Oct 2 22:46:59 EEST 2022
On 2022-09-27 10:10 am, Gyan Doshi wrote:
> The current adjustment of input start times just adjusts the tsoffset.
> And it does so, by resetting the tsoffset to nullify the new start time.
> This leads to breakage of -copyts, ignoring of user_ts_offset, breaking
> of -isync as well as breaking wrap correction.
>
> Fixed by taking cognizance of these parameters, and by correcting start
> times just before sync offsets are applied.
Comments?
> ---
> fftools/ffmpeg.c | 24 +-------------------
> fftools/ffmpeg.h | 5 ++++-
> fftools/ffmpeg_demux.c | 4 ++--
> fftools/ffmpeg_opt.c | 50 +++++++++++++++++++++++++++++++++++++-----
> 4 files changed, 52 insertions(+), 31 deletions(-)
>
> diff --git a/fftools/ffmpeg.c b/fftools/ffmpeg.c
> index 0e1477299d..fabb0fb952 100644
> --- a/fftools/ffmpeg.c
> +++ b/fftools/ffmpeg.c
> @@ -1898,7 +1898,7 @@ static void do_streamcopy(InputStream *ist, OutputStream *ost, const AVPacket *p
> start_time = 0;
> if (copy_ts) {
> start_time += f->start_time != AV_NOPTS_VALUE ? f->start_time : 0;
> - start_time += start_at_zero ? 0 : f->ctx->start_time;
> + start_time += start_at_zero ? 0 : f->enabled_start_time;
> }
> if (ist->pts >= f->recording_time + start_time) {
> close_output_stream(ost);
> @@ -3323,28 +3323,6 @@ static int transcode_init(void)
> input_streams[j + ifile->ist_index]->start = av_gettime_relative();
> }
>
> - // Correct starttime based on the enabled streams
> - for (i = 0; i < nb_input_files; i++) {
> - InputFile *ifile = input_files[i];
> - AVFormatContext *is = ifile->ctx;
> - int64_t new_start_time = INT64_MAX;
> -
> - if (is->start_time == AV_NOPTS_VALUE ||
> - !(is->iformat->flags & AVFMT_TS_DISCONT))
> - continue;
> -
> - for (int j = 0; j < is->nb_streams; j++) {
> - AVStream *st = is->streams[j];
> - if(st->discard == AVDISCARD_ALL || st->start_time == AV_NOPTS_VALUE)
> - continue;
> - new_start_time = FFMIN(new_start_time, av_rescale_q(st->start_time, st->time_base, AV_TIME_BASE_Q));
> - }
> - if (new_start_time > is->start_time) {
> - av_log(is, AV_LOG_VERBOSE, "Correcting start time by %"PRId64"\n", new_start_time - is->start_time);
> - ifile->ts_offset = -new_start_time;
> - }
> - }
> -
> /* init input streams */
> for (i = 0; i < nb_input_streams; i++)
> if ((ret = init_input_stream(i, error, sizeof(error))) < 0)
> diff --git a/fftools/ffmpeg.h b/fftools/ffmpeg.h
> index ede0b2bd96..b93c2427b6 100644
> --- a/fftools/ffmpeg.h
> +++ b/fftools/ffmpeg.h
> @@ -439,7 +439,10 @@ typedef struct InputFile {
> AVRational time_base; /* time base of the duration */
> int64_t input_ts_offset;
> int input_sync_ref;
> -
> + /**
> + * Effective format start time based on enabled streams.
> + */
> + int64_t enabled_start_time;
> int64_t ts_offset;
> /**
> * Extra timestamp offset added by discontinuity handling.
> diff --git a/fftools/ffmpeg_demux.c b/fftools/ffmpeg_demux.c
> index 6e89f5999a..6125181f81 100644
> --- a/fftools/ffmpeg_demux.c
> +++ b/fftools/ffmpeg_demux.c
> @@ -120,7 +120,7 @@ static int seek_to_start(InputFile *ifile)
> static void ts_fixup(InputFile *ifile, AVPacket *pkt, int *repeat_pict)
> {
> InputStream *ist = input_streams[ifile->ist_index + pkt->stream_index];
> - const int64_t start_time = ifile->ctx->start_time;
> + const int64_t start_time = ifile->enabled_start_time;
> int64_t duration;
>
> if (debug_ts) {
> @@ -367,7 +367,7 @@ int ifile_get_packet(InputFile *f, AVPacket **pkt)
> if (f->readrate || f->rate_emu) {
> int i;
> int64_t file_start = copy_ts * (
> - (f->ctx->start_time != AV_NOPTS_VALUE ? f->ctx->start_time * !start_at_zero : 0) +
> + (f->enabled_start_time != AV_NOPTS_VALUE ? f->enabled_start_time * !start_at_zero : 0) +
> (f->start_time != AV_NOPTS_VALUE ? f->start_time : 0)
> );
> float scale = f->rate_emu ? 1.0 : f->readrate;
> diff --git a/fftools/ffmpeg_opt.c b/fftools/ffmpeg_opt.c
> index 5febe319e4..8df322c31c 100644
> --- a/fftools/ffmpeg_opt.c
> +++ b/fftools/ffmpeg_opt.c
> @@ -293,6 +293,44 @@ static int parse_and_set_vsync(const char *arg, int *vsync_var, int file_idx, in
> return 0;
> }
>
> +/* Correct input file start times based on enabled streams */
> +static int correct_input_start_times(void)
> +{
> + for (int i = 0; i < nb_input_files; i++) {
> + InputFile *ifile = input_files[i];
> + AVFormatContext *is = ifile->ctx;
> + int64_t new_start_time = INT64_MAX, diff, abs_start_seek;
> +
> + ifile->enabled_start_time = is->start_time;
> +
> + if (is->start_time == AV_NOPTS_VALUE ||
> + !(is->iformat->flags & AVFMT_TS_DISCONT))
> + continue;
> +
> + for (int j = 0; j < is->nb_streams; j++) {
> + AVStream *st = is->streams[j];
> + if(st->discard == AVDISCARD_ALL || st->start_time == AV_NOPTS_VALUE)
> + continue;
> + new_start_time = FFMIN(new_start_time, av_rescale_q(st->start_time, st->time_base, AV_TIME_BASE_Q));
> + }
> +
> + diff = new_start_time - is->start_time;
> + if (diff) {
> + av_log(NULL, AV_LOG_VERBOSE, "Correcting start time of Input #%d by %"PRId64" us.\n", i, diff);
> + ifile->enabled_start_time = new_start_time;
> + if (copy_ts && start_at_zero)
> + ifile->ts_offset = -new_start_time;
> + else if (!copy_ts) {
> + abs_start_seek = is->start_time + (ifile->start_time != AV_NOPTS_VALUE) ? ifile->start_time : 0;
> + ifile->ts_offset = abs_start_seek > new_start_time ? -abs_start_seek : -new_start_time;
> + }
> + ifile->ts_offset += ifile->input_ts_offset;
> + }
> + }
> +
> + return 0;
> +}
> +
> static int apply_sync_offsets(void)
> {
> for (int i = 0; i < nb_input_files; i++) {
> @@ -321,9 +359,9 @@ static int apply_sync_offsets(void)
> if (self->ctx->start_time_realtime != AV_NOPTS_VALUE && ref->ctx->start_time_realtime != AV_NOPTS_VALUE) {
> self_start_time = self->ctx->start_time_realtime;
> ref_start_time = ref->ctx->start_time_realtime;
> - } else if (self->ctx->start_time != AV_NOPTS_VALUE && ref->ctx->start_time != AV_NOPTS_VALUE) {
> - self_start_time = self->ctx->start_time;
> - ref_start_time = ref->ctx->start_time;
> + } else if (self->enabled_start_time != AV_NOPTS_VALUE && ref->enabled_start_time != AV_NOPTS_VALUE) {
> + self_start_time = self->enabled_start_time;
> + ref_start_time = ref->enabled_start_time;
> } else {
> start_times_set = 0;
> }
> @@ -3747,8 +3785,6 @@ int ffmpeg_parse_options(int argc, char **argv)
> goto fail;
> }
>
> - apply_sync_offsets();
> -
> /* create the complex filtergraphs */
> ret = init_complex_filters();
> if (ret < 0) {
> @@ -3763,6 +3799,10 @@ int ffmpeg_parse_options(int argc, char **argv)
> goto fail;
> }
>
> + correct_input_start_times();
> +
> + apply_sync_offsets();
> +
> check_filter_outputs();
>
> fail:
More information about the ffmpeg-devel
mailing list