[FFmpeg-devel] [PATCH v2 2/2] ffmpeg: fix implementation of updated input start time
Gyan Doshi
ffmpeg at gyani.pro
Sat Oct 29 23:04:01 EEST 2022
Any objections?
On 2022-10-25 09:28 pm, Gyan Doshi wrote:
> Ping.
>
> On 2022-10-21 10:01 pm, 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 input_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.
>> ---
>> fftools/ffmpeg.c | 2 +-
>> fftools/ffmpeg.h | 5 ++++-
>> fftools/ffmpeg_demux.c | 4 ++--
>> fftools/ffmpeg_opt.c | 33 +++++++++++++++++++++++----------
>> 4 files changed, 30 insertions(+), 14 deletions(-)
>>
>> diff --git a/fftools/ffmpeg.c b/fftools/ffmpeg.c
>> index 0fe582be3b..c564b2649e 100644
>> --- a/fftools/ffmpeg.c
>> +++ b/fftools/ffmpeg.c
>> @@ -1815,7 +1815,7 @@ 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->start_time_effective;
>> }
>> if (ist->pts >= f->recording_time + start_time) {
>> close_output_stream(ost);
>> diff --git a/fftools/ffmpeg.h b/fftools/ffmpeg.h
>> index 5966cac60e..2d97ccaa15 100644
>> --- a/fftools/ffmpeg.h
>> +++ b/fftools/ffmpeg.h
>> @@ -447,7 +447,10 @@ 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 start_time_effective;
>> 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..220fda56da 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->start_time_effective;
>> 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->start_time_effective !=
>> AV_NOPTS_VALUE ? f->start_time_effective * !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 28b7d4dc27..a6fa9b7801 100644
>> --- a/fftools/ffmpeg_opt.c
>> +++ b/fftools/ffmpeg_opt.c
>> @@ -216,13 +216,15 @@ int parse_and_set_vsync(const char *arg, int
>> *vsync_var, int file_idx, int st_id
>> return 0;
>> }
>> +/* Correct input file start times based on enabled streams */
>> static void correct_input_start_times(void)
>> {
>> - // Correct starttime based on the enabled streams
>> 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;
>> + int64_t new_start_time = INT64_MAX, diff, abs_start_seek;
>> +
>> + ifile->start_time_effective = is->start_time;
>> if (is->start_time == AV_NOPTS_VALUE ||
>> !(is->iformat->flags & AVFMT_TS_DISCONT))
>> @@ -234,9 +236,20 @@ static void correct_input_start_times(void)
>> 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;
>> +
>> + 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->start_time_effective = 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;
>> + } else if (copy_ts)
>> + ifile->ts_offset = 0;
>> +
>> + ifile->ts_offset += ifile->input_ts_offset;
>> }
>> }
>> }
>> @@ -269,9 +282,9 @@ 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->start_time_effective != AV_NOPTS_VALUE &&
>> ref->start_time_effective != AV_NOPTS_VALUE) {
>> + self_start_time = self->start_time_effective;
>> + ref_start_time = ref->start_time_effective;
>> } else {
>> start_times_set = 0;
>> }
>> @@ -1918,8 +1931,6 @@ int ffmpeg_parse_options(int argc, char **argv)
>> goto fail;
>> }
>> - apply_sync_offsets();
>> -
>> /* create the complex filtergraphs */
>> ret = init_complex_filters();
>> if (ret < 0) {
>> @@ -1936,6 +1947,8 @@ int ffmpeg_parse_options(int argc, char **argv)
>> correct_input_start_times();
>> + apply_sync_offsets();
>> +
>> check_filter_outputs();
>> fail:
>
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