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• Do I have to reduce the GOP size for zero-latency streaming ?

  10 juin 2017, par AndreKR

  I am piping frames into FFmpeg at quite a slow rate (1 per second) and I want to stream them out with very low latency.

  There are not only sources (for example here and here) that don’t mention that I need to set the GOP size (keyint) to a small value, but there are even sources (like here and here) that explicitly say that I don’t have to set the GOP size to a small value.

  However, so far the only way I found to reduce the really long start delay is to actually reduce the GOP size to 1.

  Anyway, here’s my current command line :

  ffmpeg -f image2pipe
  
         -probesize 32
  
         -i -
  
         -c:v libx264
  
         -preset veryfast
  
         -crf 23
  
         -vsync 2
  
         -movflags "frag_keyframe+empty_moov"
  
         -profile baseline
  
         -x264-params "intra-refresh=1"
  
         -tune zerolatency
  
         -f mp4
  
         -

  (I also tried adding :bframes=0:force-ctr:no-mbtree:sync-lookahead=0:sliced-threads:rc-lookahead=0 to -x264-params (what -tune zerolatency is supposed to do) because some of those values didn’t appear in the debug output, but as expected it had no effect.)

  As you can see here, we are already 182 frames (= 3 minutes wall clock) into the stream, but it still hasn’t emitted anything (size was 1kB from the start).

  frame=  182 fps=1.0 q=20.0 size=       1kB time=00:00:07.24 bitrate=   0.8kbits/s speed=0.0402x

  This actually talks about the time-to-first-picture, but it makes it seem like it’s not a big deal. ;) It is for me, so maybe I have to make the first GOP 1 frame long and then I can switch to longer GOPs ? Can FFmpeg do that ?

• ffmpeg conversion commandline needed [migrated]

  8 avril 2014, par user3506221

  I want to ask for help on converting a mpg videofile recorded from TV
  to a mp4 format my SAT Receiver can play, (mp4).
  Below are the format infos of source and target output by ffmpeg -i :
  All done on Linux.

  source :

  Stream #0:1[0x1e0]: Video: mpeg2video (Main), yuv420p(tv), 720x576 [SAR 64:45 DAR 16:9], max. 9500 kb/s, 25 fps, 25 tbr, 90k tbn, 50 tbc
  
  Stream #0:2[0x83]: Audio: ac3, 48000 Hz, stereo, fltp, 448 kb/s

  target :

  Stream #0:0(und): Video: h264 (Main) (avc1 / 0x31637661), yuv420p(tv), 720x406 [SAR 1:1 DAR 360:203], 1894 kb/s, 25 fps, 25 tbr, 25k tbn, 50 tbc (default)
  
  Stream #0:1(und): Audio: aac (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 93 kb/s (default)

  ffmpeg -i ./source.mpg
  ffmpeg version 2.2 Copyright (c) 2000-2014 the FFmpeg developers
  built on Mar 24 2014 17:15:07 with gcc 4.8 (SUSE Linux)
  configuration : —shlibdir=/usr/lib —prefix=/usr —mandir=/usr/share/man —libdir=/usr/lib —enable-shared —disable-static —enable-debug —disable-stripping —extra-cflags='-fomit-frame-pointer -fmessage-length=0 -grecord-gcc-switches -fstack-protector -O2 -Wall -D_FORTIFY_SOURCE=2 -funwind-tables -fasynchronous-unwind-tables -g -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 -I/usr/include/gsm' —enable-gpl —enable-x11grab —enable-version3 —enable-pthreads —enable-avfilter —enable-libpulse —enable-libvpx —enable-libopus —enable-libass —enable-libx265 —enable-libmp3lame —enable-libvorbis —enable-libtheora —enable-libspeex —enable-libxvid —enable-libx264 —enable-libschroedinger —enable-libgsm —enable-libopencore-amrnb —enable-libopencore-amrwb —enable-postproc —enable-libdc1394 —enable-librtmp —enable-libfreetype —enable-avresample —enable-libtwolame —enable-libvo-aacenc —enable-gnutls
  libavutil 52. 66.100 / 52. 66.100
  libavcodec 55. 52.102 / 55. 52.102
  libavformat 55. 33.100 / 55. 33.100
  libavdevice 55. 10.100 / 55. 10.100
  libavfilter 4. 2.100 / 4. 2.100
  libavresample 1. 2. 0 / 1. 2. 0
  libswscale 2. 5.102 / 2. 5.102
  libswresample 0. 18.100 / 0. 18.100
  libpostproc 52. 3.100 / 52. 3.100
  [NULL @ 0x82baf20] start time is not set in estimate_timings_from_pts
  Input #0, mpeg, from './Rossini.mpg' :
  Duration : 01:49:08.19, start : 0.252622, bitrate : 4815 kb/s
  Stream #0:0[0x1bf] : Data : dvd_nav_packet
  Stream #0:1[0x1e0] : Video : mpeg2video (Main), yuv420p(tv), 720x576 [SAR 64:45 DAR 16:9], max. 9500 kb/s, 25 fps, 25 tbr, 90k tbn, 50 tbc
  Stream #0:2[0x83] : Audio : ac3, 48000 Hz, stereo, fltp, 448 kb/s
  At least one output file must be specified

  ffmpeg -i ./target.mp4
  ffmpeg version 2.2 Copyright (c) 2000-2014 the FFmpeg developers
  built on Mar 24 2014 17:15:07 with gcc 4.8 (SUSE Linux)
  configuration : —shlibdir=/usr/lib —prefix=/usr —mandir=/usr/share/man —libdir=/usr/lib —enable-shared —disable-static —enable-debug —disable-stripping —extra-cflags='-fomit-frame-pointer -fmessage-length=0 -grecord-gcc-switches -fstack-protector -O2 -Wall -D_FORTIFY_SOURCE=2 -funwind-tables -fasynchronous-unwind-tables -g -D_LARGEFILE_SOURCE -D_FILE_OFFSET_BITS=64 -I/usr/include/gsm' —enable-gpl —enable-x11grab —enable-version3 —enable-pthreads —enable-avfilter —enable-libpulse —enable-libvpx —enable-libopus —enable-libass —enable-libx265 —enable-libmp3lame —enable-libvorbis —enable-libtheora —enable-libspeex —enable-libxvid —enable-libx264 —enable-libschroedinger —enable-libgsm —enable-libopencore-amrnb —enable-libopencore-amrwb —enable-postproc —enable-libdc1394 —enable-librtmp —enable-libfreetype —enable-avresample —enable-libtwolame —enable-libvo-aacenc —enable-gnutls
  libavutil 52. 66.100 / 52. 66.100
  libavcodec 55. 52.102 / 55. 52.102
  libavformat 55. 33.100 / 55. 33.100
  libavdevice 55. 10.100 / 55. 10.100
  libavfilter 4. 2.100 / 4. 2.100
  libavresample 1. 2. 0 / 1. 2. 0
  libswscale 2. 5.102 / 2. 5.102
  libswresample 0. 18.100 / 0. 18.100
  libpostproc 52. 3.100 / 52. 3.100
  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from './target.mp4' :
  Metadata :
  major_brand : mp42
  minor_version : 0
  compatible_brands : isommp42
  creation_time : 2014-03-31 22:03:51
  Duration : 01:20:35.84, start : 0.000000, bitrate : 1992 kb/s
  Stream #0:0(und) : Video : h264 (Main) (avc1 / 0x31637661), yuv420p(tv), 720x406 [SAR 1:1 DAR 360:203], 1894 kb/s, 25 fps, 25 tbr, 25k tbn, 50 tbc (default)
  Metadata :
  creation_time : 2014-03-31 22:03:51
  handler_name : Mainconcept MP4 Video Media Handler
  Stream #0:1(und) : Audio : aac (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 93 kb/s (default)
  Metadata :
  creation_time : 2014-03-31 22:03:51
  handler_name : Mainconcept MP4 Sound Media Handler
  At least one output file must be specified

• Unrecognized option 'c:v' ffmpeg error for converting videos to H264

  16 mai 2015, par user3528346

  I told my server to upgrade to latest version of ffmpeg and they told me they did and I have the latest version that is 2.2.1 .
  I test several codes to convert a video to x264 , here is the one ;

  passthru("$ffmpegpath -i aatest/a.AVI -c:v libx264 -c:a libfaac -preset veryslow -qp 0 aatest/output.mp4 2>&1");

  the result

  FFmpeg version 0.6.5, Copyright (c) 2000-2010 the FFmpeg developers
  built on Jan 29 2012 17:52:15 with gcc 4.4.5 20110214 (Red Hat
  4.4.5-6) configuration : —prefix=/usr —libdir=/usr/lib64 —shlibdir=/usr/lib64 —mandir=/usr/share/man —incdir=/usr/include —disable-avisynth —extra-cflags=’-O2 -g -pipe -Wall -Wp,-D_FORTIFY_SOURCE=2 -fexceptions -fstack-protector —param=ssp-buffer-size=4 -m64 -mtune=generic -fPIC’ —enable-avfilter —enable-avfilter-lavf —enable-libdc1394 —enable-libdirac —enable-libfaac —enable-libfaad —enable-libfaadbin —enable-libgsm —enable-libmp3lame —enable-libopencore-amrnb —enable-libopencore-amrwb —enable-librtmp —enable-libschroedinger —enable-libspeex —enable-libtheora —enable-libx264 —enable-gpl —enable-nonfree —enable-postproc —enable-pthreads —enable-shared —enable-swscale —enable-vdpau —enable-version3 —enable-x11grab libavutil 50.15. 1 / 50.15. 1 libavcodec 52.72. 2 / 52.72. 2
  libavformat 52.64. 2 / 52.64. 2 libavdevice 52. 2. 0 / 52. 2. 0
  libavfilter 1.19. 0 / 1.19. 0 libswscale 0.11. 0 / 0.11. 0 libpostproc
  51. 2. 0 / 51. 2. 0 [mpeg4 @ 0x1111960]Invalid and inefficient vfw-avi packed B frames detected [mpeg4 @ 0x1111960]frame skip 8 Input #0,
  avi, from ’aatest/a.AVI’ : Duration : 00:02:04.04, start : 0.000000,
  bitrate : 885 kb/s Stream #0.0 : Video : mpeg4, yuv420p, 480x360 [PAR 4:3
  DAR 16:9], 25 tbr, 25 tbn, 25 tbc Stream #0.1 : Audio : mp3, 44100 Hz, 2
  channels, s16, 128 kb/s Unrecognized option ’c:v’

  the last line says "Unrecognized option ’c:v’"

  What should I do ?
  Thanks