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• Removing Silence from m4a files using ffmpeg

  27 juin 2015, par Tejas Shah

  I have an audio file which has both leading and trailing silence and with the following specifics :

  Codec : MPEG AAC Audio (mp4a) Channels : Stereo Sample rate : 44100 Hz Bitrate : 253 kbps

  I want to remove the silences AND keep the quality intact.

  So far I’ve tried

  ffmpeg -i 1.m4a -af silenceremove=1:0.5:0:1:0.5:0 2.m4a 

  This is supposed to remove both the leading and trailing silences.
  But for some reason it doesn’t remove the trailing silence. This seems to be a recurring problem. Found the following on another forum.

  http://ffmpeg-users.933282.n4.nabble.com/How-to-delete-digital-silence-tp4667256p4667356.html

  Also, ffmpeg reduces the bitrate to 128kbps. This I could fix by adding -ab 253k and making the command :

  ffmpeg -i 1.m4a -af silenceremove=1:0.5:0:1:0.5:0 -ab 253k 3.m4a 

  Now the problem is that the trailing silence isn’t removed and when I want to process a batch of files I can’t use the same bitrate (like 253kbps ) for every file. I’d like to know how VBR could be used for this case.

  I know I can use sox and use the silence and reverse features to trim the silences.

  http://digitalcardboard.com/blog/2009/08/25/the-sox-of-silence "Example 3 in this post"

  But sox has the following problems :

  1. It can’t handle m4a files, I had to convert all files to mp3.

  2. When using the silence filter in sox it caps the bitrate at 128kbps.

     sox 1.mp3 2.mp3 silence 1 0.5 1% reverse silence 1 0.5 1% reverse

• ffmpeg errors when playing a playlist - Non monotonous DTS

  20 novembre 2023, par Evilmachine

  i have a strange bug in ffmpeg. I am using ffmpeg to stream Twitch VODs and CLIPs to a 24/7 twitch channel. If i stream the files one by one its working. If i am streaming a playlist containing vods and clips i get this error when the shorter clips are playing :

  


  [flv @ 0x555677050c60] Non-monotonous DTS in output stream 0:0; previous: 56867, current: 31846; changing to 56867. This may result in incorrect timestamps in the output file.

  


  and the video stops. Once the playlist has a longer vod again it is working.

  


  here is my code that i use to stream :

  


  while [ 1 -eq 1 ]
do
ffmpeg  -fflags +igndts -re -f concat -safe 0 -i playlist.txt -codec copy -flvflags no_duration_filesize -f flv rtmp://XXXXXXXXX
done


  


  If i look into ffprobe the files seems both to be normal :

  


  VODs

  


  ffprobe version 5.1.3-1+rpt4 Copyright (c) 2007-2022 the FFmpeg developers
  built with gcc 12 (Debian 12.2.0-14)
  configuration: --prefix=/usr --extra-version=1+rpt4 --toolchain=hardened --incdir=/usr/include/aarch64-linux-gnu --enable-gpl --disable-stripping --disable-mmal --enable-gnutls --enable-ladspa --enable-libaom --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libcodec2 --enable-libdav1d --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libglslang --enable-libgme --enable-libgsm --enable-libjack --enable-libmp3lame --enable-libmysofa --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librabbitmq --enable-librist --enable-librubberband --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libsrt --enable-libssh --enable-libsvtav1 --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzimg --enable-libzmq --enable-libzvbi --enable-lv2 --enable-omx --enable-openal --enable-opencl --enable-opengl --enable-sand --enable-sdl2 --disable-sndio --enable-libjxl --enable-neon --enable-v4l2-request --enable-libudev --enable-epoxy --libdir=/usr/lib/aarch64-linux-gnu --arch=arm64 --enable-pocketsphinx --enable-librsvg --enable-libdc1394 --enable-libdrm --enable-vout-drm --enable-libiec61883 --enable-chromaprint --enable-frei0r --enable-libx264 --enable-libplacebo --enable-librav1e --enable-shared
  libavutil      57. 28.100 / 57. 28.100
  libavcodec     59. 37.100 / 59. 37.100
  libavformat    59. 27.100 / 59. 27.100
  libavdevice    59.  7.100 / 59.  7.100
  libavfilter     8. 44.100 /  8. 44.100
  libswscale      6.  7.100 /  6.  7.100
  libswresample   4.  7.100 /  4.  7.100
  libpostproc    56.  6.100 / 56.  6.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'Speedrun - Goof Troop - Coop - @olli_wan und luk30994 -- Disney's Goof Troop.mp4':
  Metadata:
    major_brand     : mp42
    minor_version   : 0
    compatible_brands: isommp42
    creation_time   : 2023-10-17T11:46:25.000000Z
  Duration: 00:28:23.02, start: 0.000000, bitrate: 1004 kb/s
  Stream #0:0[0x1](und): Video: h264 (High) (avc1 / 0x31637661), yuv420p(tv, bt709, progressive), 1280x720 [SAR 1:1 DAR 16:9], 873 kb/s, 30 fps, 30 tbr, 15360 tbn (default)
    Metadata:
      creation_time   : 2023-10-17T11:46:25.000000Z
      handler_name    : ISO Media file produced by Google Inc. Created on: 10/17/2023.
      vendor_id       : [0][0][0][0]
  Stream #0:1[0x2](und): Audio: aac (LC) (mp4a / 0x6134706D), 44100 Hz, stereo, fltp, 128 kb/s (default)
    Metadata:
      creation_time   : 2023-10-17T11:46:25.000000Z
      handler_name    : ISO Media file produced by Google Inc. Created on: 10/17/2023.
      vendor_id       : [0][0][0][0]


  


  CLIPS

  


  ffprobe version 5.1.3-1+rpt4 Copyright (c) 2007-2022 the FFmpeg developers
  built with gcc 12 (Debian 12.2.0-14)
  configuration: --prefix=/usr --extra-version=1+rpt4 --toolchain=hardened --incdir=/usr/include/aarch64-linux-gnu --enable-gpl --disable-stripping --disable-mmal --enable-gnutls --enable-ladspa --enable-libaom --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libcodec2 --enable-libdav1d --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libglslang --enable-libgme --enable-libgsm --enable-libjack --enable-libmp3lame --enable-libmysofa --enable-libopenjpeg --enable-libopenmpt --enable-libopus --enable-libpulse --enable-librabbitmq --enable-librist --enable-librubberband --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libsrt --enable-libssh --enable-libsvtav1 --enable-libtheora --enable-libtwolame --enable-libvidstab --enable-libvorbis --enable-libvpx --enable-libwebp --enable-libx265 --enable-libxml2 --enable-libxvid --enable-libzimg --enable-libzmq --enable-libzvbi --enable-lv2 --enable-omx --enable-openal --enable-opencl --enable-opengl --enable-sand --enable-sdl2 --disable-sndio --enable-libjxl --enable-neon --enable-v4l2-request --enable-libudev --enable-epoxy --libdir=/usr/lib/aarch64-linux-gnu --arch=arm64 --enable-pocketsphinx --enable-librsvg --enable-libdc1394 --enable-libdrm --enable-vout-drm --enable-libiec61883 --enable-chromaprint --enable-frei0r --enable-libx264 --enable-libplacebo --enable-librav1e --enable-shared
  libavutil      57. 28.100 / 57. 28.100
  libavcodec     59. 37.100 / 59. 37.100
  libavformat    59. 27.100 / 59. 27.100
  libavdevice    59.  7.100 / 59.  7.100
  libavfilter     8. 44.100 /  8. 44.100
  libswscale      6.  7.100 /  6.  7.100
  libswresample   4.  7.100 /  4.  7.100
  libpostproc    56.  6.100 / 56.  6.100
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'Clip -- Luk - Terra - Lebensweisheiten mit Lukas Thema Smart.mp4':
  Metadata:
    major_brand     : isom
    minor_version   : 512
    compatible_brands: isomiso2avc1mp41
    encoder         : Lavf57.83.100
  Duration: 00:00:05.00, start: 0.000000, bitrate: 5520 kb/s
  Stream #0:0[0x1](und): Video: h264 (Main) (avc1 / 0x31637661), yuv420p(tv, unknown/bt709/unknown, progressive), 1280x720, 5374 kb/s, 60.20 fps, 60 tbr, 15360 tbn (default)
    Metadata:
      handler_name    : VideoHandler
      vendor_id       : [0][0][0][0]
  Stream #0:1[0x2](und): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 128 kb/s (default)
    Metadata:
      handler_name    : SoundHandler
      vendor_id       : [0][0][0][0]


  


  Has someone a hint why this error happens and how i can avoid them ?
Is gstreamer better for this approach ?

  


  Thanks a lot in Advance.

  


  I tried changing the files.

  


• Problems using Intel Quick Sync H.264 Encoder with FFMPEG (shared) [closed]

  28 mai 2024, par Michael Werner
  

  • OS : Windows 11 Pro

  


  • IDE : Visual Studio 2022

  


  • PL : C++

  


  • Libraries : FFMPEG shared (own x64 Windows build with libmfx)

  


  


  I am trying to encode frames from a framegrabber card with Intel Quick Sync Encoder using libmfx in FFMPEG shared / libav but I am getting an error always. The "same" procedure using ffmpeg.exe of same build works fine.

  


  I increased the FFMPEG logging level to the maximum level. The avcodec_send_frame function always returns -22 (which means "Invalid argument"). And I do not get more information from the log output /console. The only thing the encoder is reporting is :

  


  [h264_mp4toannexb @ 0000028e41f42e00] The input looks like it is Annex B already

[h264_qsv @ 0000028e41f46980] Invalid pkt_timebase, passing timestamps as-is.


  


  The frames from the grabber card are 1920x1080 pixel YUV420P. I send them as they are to the encoder setting following FFMPEG video codec context options :

  


  

  • bit_rate : 5000000

  


  • width : 1920

  


  • height : 1080

  


  • framerate : 50, 1

  


  • max_b_frames : 3

  


  • pix_fmt : AV_PIX_FMT_YUV420P

  


  


  Actually I do not set any private encoder options.

  


  Does anyone have an idea what I am doing wrong or what is missing ? Is there a way to increase the debug output of libmfx ? I do not find anything related in the encoders private options.