From 694545b6d5fff5a8242b5fab8c1746e74a06f9ba Mon Sep 17 00:00:00 2001 From: "Shiwang.Xie" Date: Sat, 15 May 2021 08:53:56 +0000 Subject: [PATCH] fftools/ffmpeg: fix -t inaccurate recording time if input start time is not 0 -t is inaccurate doing stream copy, will record extra duration according to input start time. it should base on following cases: input video start time from 60s, duration is 300s, 1. stream copy: ffmpeg -ss 40 -t 60 -i in.mp4 -c copy -y out.mp4 open_input_file() will seek to 100 and set ts_offset to -100, process_input() will offset pkt->pts with ts_offset to make it 0, so when do_streamcopy() with -t, exits when ist->pts >= recording_time. 2. stream copy with -copyts: ffmpeg -ss 40 -t 60 -copyts -i in.mp4 -c copy -y out.mp4 open_input_file() will seek to 100 and set ts_offset to 0, process_input() will keep raw pkt->pts as ts_offset is 0, so when do_streamcopy() with -t, exits when ist->pts >= (recording_time+f->start_time+f->ctx->start_time). 3. stream copy with -copyts -start_at_zero: ffmpeg -ss 40 -t 60 -copyts -start_at_zero -i in.mp4 -c copy -y out.mp4 open_input_file() will seek to 120 and set ts_offset to -60 as start_to_zero option, process_input() will offset pkt->pts with input file start time, so when do_streamcopy() with -t, exits when ist->pts >= (recording_time+f->start_time). 0 60 40 60 360 |_______|_____|_______|_______________________| start -ss -t This fixes ticket #9141. Signed-off-by: Shiwang.Xie --- fftools/ffmpeg.c | 8 +++++--- 1 file changed, 5 insertions(+), 3 deletions(-) diff --git a/fftools/ffmpeg.c b/fftools/ffmpeg.c index e0f2fe138f..3ca93fc8fa 100644 --- a/fftools/ffmpeg.c +++ b/fftools/ffmpeg.c @@ -2088,9 +2088,11 @@ static void do_streamcopy(InputStream *ist, OutputStream *ost, const AVPacket *p } if (f->recording_time != INT64_MAX) { - start_time = f->ctx->start_time; - if (f->start_time != AV_NOPTS_VALUE && copy_ts) - start_time += f->start_time; + 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; + } if (ist->pts >= f->recording_time + start_time) { close_output_stream(ost); return;