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• Ffmpeg inaccurate cutting with ts and m3u8 files despite resamping audio filter

  31 juillet 2020, par Lemon Sky

  I need to accurately seek and cut a video. Some online sources say put -ss in front or after the source. The result is the same for me. In the examples below, the start time is accurate but the duration is not accurate.

  


  ffmpeg -y -ss 00:00:05 -t 00:00:05 -i output.ts 5s.wav
ffprobe 5s.wav

Duration: 00:00:04.74

ffmpeg -y -i output.ts -ss 00:00:05 -t 00:00:05 5s.wav
ffprobe 5s.wav

Duration: 00:00:04.74


  


  Sometimes the starting point is not accurate but the duration is. This is clearly audible by cutting the ts file and cutting an uncompressed wav file, and listening to both.

  


  ffmpeg -y -i output.ts -ss 00:00:15 -t 00:00:05 5s.wav

ffmpeg -y -i output.wav -ss 00:00:15 -t 00:00:05 5s-reference.wav


  


  What fixes the starting time is if I use an m3u8 file that contains the byte offset for every keyframe AND I put the -ss option in front of the source file (if I put it after the source, the start time is inaccurate but the duration is accurate) :

  


  ffmpeg -y -ss 00:00:15 -t 00:00:05 -i output.m3u8 5s.wav


  


  This fixes the start time but the duration is at the location that I would get had I used no m3u8 file (duration is just 4.47s).

  


  It seems different timestamps are involved, and sometimes one or the other gets used.

  


  The ts file was generated by capturing a UDP stream and storing it with ffmpeg and -codec:v copy.

  


  Is ffmpeg broken, or the ts file ? How do I work around this issue or fix the ts file ? What I realize is that the video starts later than the audio, probably because the video does not start with a keyframe. Can I get ffmpeg to start the -codec:v copy after the first keyframe ? What I also notice is that using ffprobe reports "start : 1.400000". Can I force it to start at 0 ?

  


  Any hints would be appreciated.

  


  I tried both ffmpeg 4.3.1 and ffmpeg git-2020-07-24-21442a8.

  


  The output.* files were generated as follows. The statement "af aresample=async=1" should fill missing audio according to Duration of source video and subtracted audio are different. Adding this statement makes no difference in terms of accuracy or duration. The question is not a duplicate.

  


  ffmpeg -i udp://example:port ^
-af aresample=async=1 ^
-codec:v copy ^
-codec:a aac -ac 2 -ar 44100 -b:a 160k ^
-hls_time 4 -hls_flags single_file -hls_list_size 0 -hls_segment_filename output.ts -hls_segment_type mpegts output.m3u8 ^
-codec:a pcm_s16le -bitexact -ar 11025 -ac 1 output.wav


  


• Ffmpeg inaccurate cut duration with ts [duplicate]

  30 juillet 2020, par Lemon Sky

  I need to accurately seek and cut a video. Some online sources say put -ss in front or after the source. The result is the same for me. In the examples below, the start time is accurate but the duration is not accurate.

  


  ffmpeg -y -ss 00:00:05 -t 00:00:05 -i http://tyberis.com/output.ts 5s.wav
ffprobe 5s.wav

Duration: 00:00:04.74

ffmpeg -y -i http://tyberis.com/output.ts -ss 00:00:05 -t 00:00:05 5s.wav
ffprobe 5s.wav

Duration: 00:00:04.74


  


  Sometimes the starting point is not accurate but the duration is. This is clearly audible by cutting the ts file and cutting an uncompressed wav file, and listening to both.

  


  ffmpeg -y -i http://tyberis.com/output.ts -ss 00:00:15 -t 00:00:05 5s.wav

ffmpeg -y -i http://tyberis.com/output.wav -ss 00:00:15 -t 00:00:05 5s-reference.wav


  


  What fixes the starting time is if I use an m3u8 file that contains the byte offset for every keyframe AND I put the -ss option in front of the source file (if I put it after the source, the start time is inaccurate but the duration is accurate) :

  


  ffmpeg -y -ss 00:00:15 -t 00:00:05 -i http://tyberis.com/output.m3u8 5s.wav


  


  This fixes the start time but the duration is at the location that I would get had I used no m3u8 file (duration is just 4.47s).

  


  It seems different timestamps are involved, and sometimes one or the other gets used.

  


  The ts file was generated by capturing a UDP stream and storing it with ffmpeg and -codec:v copy.

  


  Is ffmpeg broken, or the ts file ? How do I work around this issue or fix the ts file ? What I realize is that the video starts later than the audio, probably because the video does not start with a keyframe. Can I get ffmpeg to start the -codec:v copy after the first keyframe ? What I also notice is that using ffprobe reports "start : 1.400000". Can I force it to start at 0 ?

  


  Any hints would be appreciated.

  


  I tried both ffmpeg 4.3.1 and ffmpeg git-2020-07-24-21442a8.

  


• ffmpeg : LIVE HLS Playback getting delayed over time

  31 juillet 2020, par Krishnakumar

  We are converting UDP Input to Live HLS output and pushing the chunks to a webdav server. Initial playback works fine, But the playback was delayed by almost an hour, when we checked after 15 hours. Not sure this is caused due to network as we use internet to push the chunks. Below is the ffmpeg command used.

  


  ffmpeg -i udp://230.1.1.15:10000?fifo_size=10000000&overrun_nonfatal=1 -filter_complex [i:0xd49]yadif,setdar=256/144[v0];[i:0xd49]yadif,setdar=512/288[v1];[i:0xd49]yadif,setdar=640/360[v2];[i:0xd49]yadif,setdar=1280/720[v3] -f hls -map i:0xd4a -af aresample=async=1:min_hard_comp=0.100000:first_pts=0 -c:a:0 libfdk_aac -b:a:0 48000 -ar:0 48000 -map [v0] -b:v:0 100000 -maxrate:v:0 100000 -minrate:v:0 100000 -bufsize:v:0 200000 -s:v:0 256x144 -r:0 25 -sc_threshold 0 -pix_fmt yuv420p -flags +global_header+cgop -c:v:0 libx264 -profile:v:0 baseline -level:v:0 3.0 -preset:v:0 fast -nal-hrd cbr -g 50 -map i:0xd4a -af aresample=async=1:min_hard_comp=0.100000:first_pts=0 -c:a:1 libfdk_aac -b:a:1 48000 -ar:1 48000 -map [v1] -b:v:1 200000 -maxrate:v:1 200000 -minrate:v:1 200000 -bufsize:v:1 400000 -s:v:1 512x288 -r:1 25 -sc_threshold 0 -pix_fmt yuv420p -flags +global_header+cgop -c:v:1 libx264 -profile:v:1 baseline -level:v:1 3.0 -preset:v:1 fast -nal-hrd cbr -g 50 -map i:0xd4a -af aresample=async=1:min_hard_comp=0.100000:first_pts=0 -c:a:2 libfdk_aac -b:a:2 64000 -ar:2 48000 -map [v2] -b:v:2 700000 -maxrate:v:2 700000 -minrate:v:2 700000 -bufsize:v:2 1400000 -s:v:2 640x360 -r:2 25 -sc_threshold 0 -pix_fmt yuv420p -flags +global_header+cgop -c:v:2 libx264 -profile:v:2 baseline -level:v:2 3.0 -preset:v:2 fast -nal-hrd cbr -g 50 -map i:0xd4a -af aresample=async=1:min_hard_comp=0.100000:first_pts=0 -c:a:3 libfdk_aac -b:a:3 64000 -ar:3 48000 -map [v3] -b:v:3 1000000 -maxrate:v:3 1000000 -minrate:v:3 1000000 -bufsize:v:3 2000000 -s:v:3 1280x720 -r:3 25 -sc_threshold 0 -pix_fmt yuv420p -flags +global_header+cgop -c:v:3 libx264 -profile:v:3 high -level:v:3 4.0 -preset:v:3 fast -nal-hrd cbr -g 50 -var_stream_map a:0,v:0,name:148k a:1,v:1,name:248k a:2,v:2,name:764k a:3,v:3,name:1064k -master_pl_name master.m3u8 -hls_list_size 3 -hls_time 6 -hls_segment_filename https://usr:pass@example.com:8043/httppush/media_%v_%03d.ts -hls_flags delete_segments+independent_segments+discont_start https://usr:pass@example.com:8043/httppush/playlist_%v.m3u8


  


  FFMPEG V4.3

  


  ffmpeg version 4.3 Copyright (c) 2000-2020 the FFmpeg developers
  built with gcc 4.8.5 (GCC) 20150623 (Red Hat 4.8.5-36)
  configuration: --prefix=/root/ffmpeg_build --pkg-config-flags=--static --extra-cflags=-I/root/ffmpeg_build/include --extra-ldflags=-L/root/ffmpeg_build/lib --extra-libs=-lpthread --extra-libs=-lm --bindir=/root/bin --enable-gpl --enable-libfdk_aac --enable-libfreetype --enable-libmp3lame --enable-libopus --enable-libvpx --enable-libx264 --enable-libx265 --enable-nonfree --enable-openssl
  libavutil      56. 51.100 / 56. 51.100
  libavcodec     58. 91.100 / 58. 91.100
  libavformat    58. 45.100 / 58. 45.100
  libavdevice    58. 10.100 / 58. 10.100
  libavfilter     7. 85.100 /  7. 85.100
  libswscale      5.  7.100 /  5.  7.100
  libswresample   3.  7.100 /  3.  7.100
  libpostproc    55.  7.100 / 55.  7.100


  


  With Split Filter :

  


  ffmpeg -i "udp://230.1.1.15:10000?fifo_size=10000000&overrun_nonfatal=1" -filter_complex "[i:0xd49]yadif[v];[v]split=4[1out1][1out2][1out3][1out4];[1out1]setdar=256/144[v0];[1out2]setdar=512/288[v1];[1out3]setdar=640/360[v2];[1out4]setdar=1280/720[v3];[i:0xd4a]aresample=async=1:min_hard_comp=0.100000:first_pts=0[a];[a]asplit=4[a0][a1][a2][a3]" -f hls -map [a0] -c:a:0 libfdk_aac -b:a:0 48000 -ar:0 48000 -map [v0] -b:v:0 100000 -maxrate:v:0 100000 -minrate:v:0 100000 -bufsize:v:0 200000 -s:v:0 256x144 -r:0 25 -sc_threshold 0 -pix_fmt yuv420p -flags +global_header+cgop -c:v:0 libx264 -profile:v:0 baseline -level:v:0 3.0 -preset:v:0 fast -nal-hrd cbr -g 50 -map [a1] -c:a:1 libfdk_aac -b:a:1 48000 -ar:1 48000 -map [v1] -b:v:1 200000 -maxrate:v:1 200000 -minrate:v:1 200000 -bufsize:v:1 400000 -s:v:1 512x288 -r:1 25 -sc_threshold 0 -pix_fmt yuv420p -flags +global_header+cgop -c:v:1 libx264 -profile:v:1 baseline -level:v:1 3.0 -preset:v:1 fast -nal-hrd cbr -g 50 -map [a2] -c:a:2 libfdk_aac -b:a:2 64000 -ar:2 48000 -map [v2] -b:v:2 700000 -maxrate:v:2 700000 -minrate:v:2 700000 -bufsize:v:2 1400000 -s:v:2 640x360 -r:2 25 -sc_threshold 0 -pix_fmt yuv420p -flags +global_header+cgop -c:v:2 libx264 -profile:v:2 baseline -level:v:2 3.0 -preset:v:2 fast -nal-hrd cbr -g 50 -map [a3] -c:a:3 libfdk_aac -b:a:3 64000 -ar:3 48000 -map [v3] -b:v:3 1000000 -maxrate:v:3 1000000 -minrate:v:3 1000000 -bufsize:v:3 2000000 -s:v:3 1280x720 -r:3 25 -sc_threshold 0 -pix_fmt yuv420p -flags +global_header+cgop -c:v:3 libx264 -profile:v:3 high -level:v:3 4.0 -preset:v:3 fast -nal-hrd cbr -g 50 -var_stream_map "a:0,v:0,name:148k a:1,v:1,name:248k a:2,v:2,name:764k a:3,v:3,name:1064k" -master_pl_name master.m3u8 -hls_list_size 3 -hls_time 6 -hls_segment_filename https://usr:pass@example.com:8043/httppush/media_%v_%03d.ts -hls_flags delete_segments+independent_segments+discont_start https://usr:pass@example.com:8043/httppush/playlist_%v.m3u8