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• FFmpeg video overlay function not working

  5 novembre 2022, par Dennis Ashford

  I am simply trying to get a watermarked video from the Flutter FFmpeg package and cannot seem to get it to work. Right now, I am downloading the video from Firebase, storing it in cache, overlaying a watermark image using the Flutter FFmpeg Kit package. The original video file, image file, and output file are being created properly.

  


  However, the overlay function is not working properly. How can I use the FFmpegKit.execute function string ? I am not seeing any obvious errors in the function, but it isn't working properly. I tried writing as a new File and asBytes but neither worked.

  


  Edit : I want to take the originalVideo and overlay it with the watermark image with the expected outcome being a new file that contains the new overlayed video. Not concerned with where the overlay is yet.

  


  Pubspec.yaml

  


  ffmpeg_kit_flutter: ^4.5.1


  


  The function is :

  


  import &#x27;package:ffmpeg_kit_flutter/ffmpeg_kit.dart&#x27;;&#xA;&#xA;Future<file> waterMarkVideo(String videoPath, String watermarkPath) async {&#xA;    //these calls are to load the video into temporary directory&#xA;    final response = await http.get(Uri.parse(videoPath));&#xA;    final originalVideo = File (&#x27;${(await getTemporaryDirectory()).path}/video.mp4&#x27;);&#xA;    await originalVideo.create(recursive: true);&#xA;    await originalVideo.writeAsBytes(response.bodyBytes);&#xA;    print(&#x27;video path&#x27; &#x2B; originalVideo.path);&#xA;&#xA;    //this grabs the watermark image from assets and decodes it&#xA;    final byteData = await rootBundle.load(watermarkPath);&#xA;    final watermark = File(&#x27;${(await getTemporaryDirectory()).path}/image.png&#x27;);&#xA;    await watermark.create(recursive: true);&#xA;    await watermark.writeAsBytes(byteData.buffer.asUint8List(byteData.offsetInBytes, byteData.lengthInBytes));&#xA;    print(&#x27;watermark path&#x27; &#x2B; watermark.path);&#xA;&#xA;    //this creates temporary directory for new watermarked video&#xA;    var tempDir = await getTemporaryDirectory();&#xA;    final newVideoPath = &#x27;${tempDir.path}/${DateTime.now().microsecondsSinceEpoch}result.mp4&#x27;;&#xA;    final videoFile = await File(newVideoPath).create();&#xA;&#xA;//overlaying video using FFmpegkit where I need some help&#xA;    await FFmpegKit.executeAsync("-i $originalVideo -i $watermark -filter_complex &#x27;overlay=(W-w)/2:(H-h)/2&#x27; $videoFile")&#xA;    .then((session) async {&#xA;      final state = FFmpegKitConfig.sessionStateToString(await session.getState());&#xA;      final returnCode = await session.getReturnCode();&#xA;      final failStackTrace = await session.getFailStackTrace();&#xA;      final output = await session.getOutput();&#xA;      print(&#x27;FFmpeg process exited with state ${state} and rs ${returnCode}.If failed ${failStackTrace}&#x27;);&#xA;      print(&#x27;Last output $output&#x27;);&#xA;    } );&#xA;    print(&#x27;new video path&#x27; &#x2B; newVideoPath);&#xA;    Uint8List videoByteData = await videoFile.readAsBytes();&#xA;    return videoFile.writeAsBytes(videoByteData);&#xA;}&#xA;</file>

  


  The output for the function above is

  


  flutter: video path/Users/dennisashford/Library/Developer/CoreSimulator/Devices/FBFB4D51-EC31-47DF-8FE0-66B114806EA4/data/Containers/Data/Application/0EA3BB35-D364-4B98-A104-15CDB17AAD54/Library/Caches/video.mp4
flutter: watermark path/Users/dennisashford/Library/Developer/CoreSimulator/Devices/FBFB4D51-EC31-47DF-8FE0-66B114806EA4/data/Containers/Data/Application/0EA3BB35-D364-4B98-A104-15CDB17AAD54/Library/Caches/image.png
ffmpeg version v4.5-dev-3393-g30322ebe3c Copyright (c) 2000-2021 the FFmpeg developers
  built with Apple clang version 13.0.0 (clang-1300.0.29.30)
  configuration: --cross-prefix=x86_64-ios-darwin- --sysroot=/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator15.2.sdk --prefix=/Users/taner/Projects/ffmpeg-kit/prebuilt/apple-ios-x86_64/ffmpeg --pkg-config=/opt/homebrew/bin/pkg-config --enable-version3 --arch=x86_64 --cpu=x86_64 --target-os=darwin --disable-neon --disable-asm --ar=/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/ar --cc=clang --cxx=clang++ --as='clang -arch x86_64 -target x86_64-apple-ios12.1-simulator -march=x86-64 -msse4.2 -mpopcnt -m64 -DFFMPEG_KIT_X86_64 -Wno-unused-function -Wno-deprecated-declarations -fstrict-aliasing -DIOS -DFFMPEG_KIT_BUILD_DATE=20220114 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator15.2.sdk -O2 -mios-simulator-version-min=12.1 -I/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator15.2.sdk/usr/include' --ranlib=/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/ranlib --strip=/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/strip --nm=/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm --extra-ldflags='-mios-simulator-version-min=12.1' --disable-autodetect --enable-cross-compile --enable-pic --enable-inline-asm --enable-optimizations --enable-swscale --enable-shared --disable-static --install-name-dir='@rpath' --enable-pthreads --disable-v4l2-m2m --disable-outdev=v4l2 --disable-outdev=fbdev --disable-indev=v4l2 --disable-indev=fbdev --enable-small --disable-xmm-clobber-test --disable-debug --disable-neon-clobber-test --disable-programs --disable-postproc --disable-doc --disable-htmlpages --disable-manpages --disable-podpages --disable-txtpages --disable-sndio --disable-schannel --disable-securetransport --disable-xlib --disable-cuda --disable-cuvid --disable-nvenc --disable-vaapi --disable-vdpau --disable-alsa --disable-cuda --disable-cuvid --disable-nvenc --disable-vaapi --disable-vdpau --enable-gmp --enable-gnutls --disable-sdl2 --disable-openssl --enable-zlib --enable-audiotoolbox --disable-outdev=audiotoolbox --enable-bzlib --enable-videotoolbox --enable-avfoundation --enable-iconv --disable-coreimage --disable-appkit --disable-opencl --disable-opengl
  libavutil      57. 13.100 / 57. 13.100
  libavcodec     59. 15.102 / 59. 15.102
  libavformat    59. 10.100 / 59. 10.100
  libavdevice    59.  1.100 / 59.  1.100
  libavfilter     8. 21.100 /  8. 21.100
  libswscale      6.  1.102 /  6.  1.102
  libswresample   4.  0.100 /  4.  0.100
File:: Protocol not found
Did you mean file:File:?
flutter: FFmpeg process exited with state RUNNING and rs 1.If failed null
flutter: Last output ffmpeg version v4.5-dev-3393-g30322ebe3c Copyright (c) 2000-2021 the FFmpeg developers
flutter:   built with Apple clang version 13.0.0 (clang-1300.0.29.30)
flutter:   configuration: --cross-prefix=x86_64-ios-darwin- --sysroot=/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator15.2.sdk --prefix=/Users/taner/Projects/ffmpeg-kit/prebuilt/apple-ios-x86_64/ffmpeg --pkg-config=/opt/homebrew/bin/pkg-config --enable-version3 --arch=x86_64 --cpu=x86_64 --target-os=darwin --disable-neon --disable-asm --ar=/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/ar --cc=clang --cxx=clang++ --as='clang -arch x86_64 -target x86_64-apple-ios12.1-simulator -march=x86-64 -msse4.2 -mpopcnt -m64 -DFFMPEG_KIT_X86_64 -Wno-unused-function -Wno-deprecated-declarations -fstrict-aliasing -DIOS -DFFMPEG_KIT_BUILD_DATE=20220114 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator15.2.sdk -O2 -mios-simulator-version-min=12.1 -I/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneSimulator.platform/Developer/SDKs/iPhoneSimulator15.2.sdk/usr/include' --ranlib=/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/ranlib --strip=/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/strip --nm=/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm --extra-ldflags='-mios-simulator-version-min=12.1' --disable-autodetect --enable-cross-compile --enable-pic --enable-inline-asm --enable-optimizations --enable-swscale --enable-shared --disable-static --install-name-dir='@rpath' --enable-pthreads --disable-v4l2-m2m --disable-outdev=v4l2 --disable-outdev=fbdev --disable-indev=v4l2 --disable-indev=fbdev --enable-small --disable-xmm-clobber-test --disable-debug --disable-neon-clobber-test --disable-programs --disable-postproc --disable-doc --disable-htmlpages --disable-manpages --disable-podpages --disable-txtpages --disable-sndio --disable-schannel --disable-securetransport --disable-xlib --disable-cuda --disable-cuvid --disable-nvenc --disable-vaapi --disable-vdpau --disable-alsa --disable-cuda --disable-cuvid --disable-nvenc --disable-vaapi --disable-vdpau --enable-gmp --enable-gnutls --disable-sdl2 --disable-openssl --enable-zlib --enable-audiotoolbox --disable-outdev=audiotoolbox --enable-bzlib --enable-videotoolbox --enable-avfoundation --enable-iconv --disable-coreimage --disable-appkit --disable-opencl --disable-opengl
flutter:   libavutil      57. 13.100 / 57. 13.100
flutter:   libavcodec     59. 15.102 / 59. 15.102
flutter:   libavformat    59. 10.100 / 59. 10.100
flutter:   libavdevice    59.  1.100 / 59.  1.100
flutter:   libavfilter     8. 21.100 /  8. 21.100
flutter:   libswscale      6.  1.102 /  6.  1.102
flutter:   libswresample   4.  0.100 /  4.  0.100
flutter: File:: Protocol not found
flutter: Did you mean file:File:?
flutter: 
flutter: new video path/Users/dennisashford/Library/Developer/CoreSimulator/Devices/FBFB4D51-EC31-47DF-8FE0-66B114806EA4/data/Containers/Data/Application/0EA3BB35-D364-4B98-A104-15CDB17AAD54/Library/Caches/1661892011213545result.mp4


  


  Update : So I built the code on a physical device and was able to get a little more information for what may be the problem. The error may be coming from

  


  File:: Protocol not found
Did you mean file:File:?


  


  Complete logs from the physical device are given below

  


  flutter: video path/var/mobile/Containers/Data/Application/70EA92CD-DF5D-440E-BBE1-C130BC7F0CC7/Library/Caches/video.mp4
flutter: watermark path/var/mobile/Containers/Data/Application/70EA92CD-DF5D-440E-BBE1-C130BC7F0CC7/Library/Caches/image.png
ffmpeg version v4.5-dev-3393-g30322ebe3c Copyright (c) 2000-2021 the FFmpeg developers
  built with Apple clang version 13.0.0 (clang-1300.0.29.30)
  configuration: --cross-prefix=arm64-ios-darwin- --sysroot=/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS15.2.sdk --prefix=/Users/taner/Projects/ffmpeg-kit/prebuilt/apple-ios-arm64/ffmpeg --pkg-config=/opt/homebrew/bin/pkg-config --enable-version3 --arch=aarch64 --cpu=armv8 --target-os=darwin --enable-neon --enable-asm --ar=/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/ar --cc=clang --cxx=clang++ --as='/Users/taner/Projects/ffmpeg-kit/.tmp/gas-preprocessor.pl -arch aarch64 -- clang -arch arm64 -target arm64-apple-ios12.1 -march=armv8-a+crc+crypto -mcpu=generic -DFFMPEG_KIT_ARM64 -Wno-unused-function -Wno-deprecated-declarations -fstrict-aliasing -fembed-bitcode -DIOS -DFFMPEG_KIT_BUILD_DATE=20220114 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS15.2.sdk -Oz -miphoneos-version-min=12.1 -I/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS15.2.sdk/usr/include' --ranlib=/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/ranlib --strip=/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/strip --nm=/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm --extra-ldflags='-miphoneos-version-min=12.1' --disable-autodetect --enable-cross-compile --enable-pic --enable-inline-asm --enable-optimizations --enable-swscale --enable-shared --disable-static --install-name-dir='@rpath' --enable-pthreads --disable-v4l2-m2m --disable-outdev=v4l2 --disable-outdev=fbdev --disable-indev=v4l2 --disable-indev=fbdev --enable-small --disable-xmm-clobber-test --disable-debug --disable-neon-clobber-test --disable-programs --disable-postproc --disable-doc --disable-htmlpages --disable-manpages --disable-podpages --disable-txtpages --disable-sndio --disable-schannel --disable-securetransport --disable-xlib --disable-cuda --disable-cuvid --disable-nvenc --disable-vaapi --disable-vdpau --disable-alsa --disable-cuda --disable-cuvid --disable-nvenc --disable-vaapi --disable-vdpau --enable-gmp --enable-gnutls --disable-sdl2 --disable-openssl --enable-zlib --enable-audiotoolbox --disable-outdev=audiotoolbox --enable-bzlib --enable-videotoolbox --enable-avfoundation --enable-iconv --disable-coreimage --disable-appkit --disable-opencl --disable-opengl
  libavutil      57. 13.100 / 57. 13.100
  libavcodec     59. 15.102 / 59. 15.102
  libavformat    59. 10.100 / 59. 10.100
  libavdevice    59.  1.100 / 59.  1.100
  libavfilter     8. 21.100 /  8. 21.100
  libswscale      6.  1.102 /  6.  1.102
  libswresample   4.  0.100 /  4.  0.100
File:: Protocol not found
Did you mean file:File:?
flutter: FFmpeg process exited with state RUNNING and rs 1.If failed null
flutter: Last output ffmpeg version v4.5-dev-3393-g30322ebe3c Copyright (c) 2000-2021 the FFmpeg developers
  built with Apple clang version 13.0.0 (clang-1300.0.29.30)
  configuration: --cross-prefix=arm64-ios-darwin- --sysroot=/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS15.2.sdk --prefix=/Users/taner/Projects/ffmpeg-kit/prebuilt/apple-ios-arm64/ffmpeg --pkg-config=/opt/homebrew/bin/pkg-config --enable-version3 --arch=aarch64 --cpu=armv8 --target-os=darwin --enable-neon --enable-asm --ar=/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/ar --cc=clang --cxx=clang++ --as='/Users/taner/Projects/ffmpeg-kit/.tmp/gas-preprocessor.pl -arch aarch64 -- clang -arch arm64 -target arm64-apple-ios12.1 -march=armv8-a+crc+crypto -mcpu=generic -DFFMPEG_KIT_ARM64 -Wno-unused-function -Wno-deprecated-declarations -fstrict-aliasing -fembed-bitcode -DIOS -DFFMPEG_KIT_BUILD_DATE=20220114 -isysroot /Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS15.2.sdk -Oz -miphoneos-version-min=12.1 -I/Applications/Xcode.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS15.2.sdk/usr/include' --ranlib=/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/ranlib --strip=/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/strip --nm=/Applications/Xcode.app/Contents/Developer/Toolchains/XcodeDefault.xctoolchain/usr/bin/nm --extra-ldflags='-miphoneos-version-min=12.1' --disable-autodetect --enable-cross-compile --enable-pic --enable-inline-asm --enable-optimizations --enable-swscale --enable-shared --disable-static --install-name-dir='@rpath' --enable-pthreads --disable-v4l2-m2m --disable-outdev=v4l2 --disable-outdev=fbdev --disable-indev=v4l2 --disable-indev=fbdev --enable-small --disable-xmm-clobber-test --disable-debug --disable-neon-clobber-test --disable-programs --disable-postproc --disable-doc --disable-htmlpages --disable-manpages --disable-podpages --disable-txtpages --disable-sndio --disable-schannel --disable-securetransport --disable-xlib --disable-cuda --disable-cuvid --disable-nvenc --disable-vaapi --disable-vdpau --disable-alsa --disable-cuda --disable-cuvid --disable-nvenc --disable-vaapi --disable-vdpau --enable-gmp --enable-gnutls --disable-sdl2 --disable-openssl --enable-zlib --enable-audiotoolbox --disable-outdev=audiotoolbox --enable-bzlib --enable-videotoolbox --enable-avfoundation --enable-iconv --disable-coreimage --disable-appkit --disable-opencl --disable-opengl
  libavutil      57. 13.100 / 57. 13.100
  libavcodec     59. 15.102 / 59. 15.102
  libavformat    59. 10.100 / 59. 10.100
  libavdevice    59.  1.100 / 59.  1.100
  libavfilter     8. 21.100 /  8. 21.100
  libswscale      6.  1.102 /  6.  1.102
  libswresample   4.  0.100 /  4.  0.100
File:: Protocol not found
Did you mean file:File:?
flutter: new video path/var/mobile/Containers/Data/Application/70EA92CD-DF5D-440E-BBE1-C130BC7F0CC7/Library/Caches/1661891272856433result.mp4


  


  Update #2 after a lot of help from @kesh below, this function was actually able to overlay the image on the video.

  


  await FFmpegKit.executeAsync('-i $videoPath -i ${watermark.path} -filter_complex "overlay=10:10" -y ${videoFile.path}')


  


• FFMPEG command not working on Ubuntu

  7 novembre 2016, par brijesh kumar

  I stuck with the command "anequalizer" in ffmpeg. I’m following the official documantation. It has example command in documentation like this

  anequalizer=c0 f=200 w=100 g=-10 t=1|c1 f=200 w=100 g=-10 t=1

  and when I run the command

  ffmpeg /home/overtatech-1/Music/jeena.mp3 -af "anequalizer=c0 f=200 w=100 g=-10 t=1|c1 f=200 w=100 g=-10 t=1" /home/overtatech-1/Music/jeena_new.mp3

  on console, I get error "c1:Command not found"

  Lenovo-G50-80:~$ ffmpeg /home/overtatech-1/Music/jeena.mp3 -af  "anequalizer=c0 f=200 w=100 g=-10 t=1|c1 f=200 w=100 g=-10 t=1" /home/overtatech-1/Music/jeena_new.mp3
  
  ffmpeg version 2.8.8-0ubuntu0.16.04.1 Copyright (c) 2000-2016 the FFmpeg developers
  
  built with gcc 5.4.0 (Ubuntu 5.4.0-6ubuntu1~16.04.2) 20160609
  
  configuration: --prefix=/usr --extra-version=0ubuntu0.16.04.1 --build-suffix=-ffmpeg --toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --cc=cc --cxx=g++ --enable-gpl --enable-shared --disable-stripping --disable-decoder=libopenjpeg --disable-decoder=libschroedinger --enable-avresample --enable-avisynth --enable-gnutls --enable-ladspa --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libmodplug --enable-libmp3lame --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-librtmp --enable-libschroedinger --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxvid --enable-libzvbi --enable-openal --enable-opengl --enable-x11grab --enable-libdc1394 --enable-libiec61883 --enable-libzmq --enable-frei0r --enable-libx264 --enable-libopencv
  
  WARNING: library configuration mismatch
  
  avcodec     configuration: --prefix=/usr --extra-version=0ubuntu0.16.04.1 --build-suffix=-ffmpeg --toolchain=hardened --libdir=/usr/lib/x86_64-linux-gnu --incdir=/usr/include/x86_64-linux-gnu --cc=cc --cxx=g++ --enable-gpl --enable-shared --disable-stripping --disable-decoder=libopenjpeg --disable-decoder=libschroedinger --enable-avresample --enable-avisynth --enable-gnutls --enable-ladspa --enable-libass --enable-libbluray --enable-libbs2b --enable-libcaca --enable-libcdio --enable-libflite --enable-libfontconfig --enable-libfreetype --enable-libfribidi --enable-libgme --enable-libgsm --enable-libmodplug --enable-libmp3lame --enable-libopenjpeg --enable-libopus --enable-libpulse --enable-librtmp --enable-libschroedinger --enable-libshine --enable-libsnappy --enable-libsoxr --enable-libspeex --enable-libssh --enable-libtheora --enable-libtwolame --enable-libvorbis --enable-libvpx --enable-libwavpack --enable-libwebp --enable-libx265 --enable-libxvid --enable-libzvbi --enable-openal --enable-opengl --enable-x11grab --enable-libdc1394 --enable-libiec61883 --enable-libzmq --enable-frei0r --enable-libx264 --enable-libopencv --enable-version3 --disable-doc --disable-programs --disable-avdevice --disable-avfilter --disable-avformat --disable-avresample --disable-postproc --disable-swscale --enable-libopencore_amrnb --enable-libopencore_amrwb --enable-libvo_aacenc --enable-libvo_amrwbenc
  
  libavutil      54. 31.100 / 54. 31.100
  
  libavcodec     56. 60.100 / 56. 60.100
  
  libavformat    56. 40.101 / 56. 40.101
  
  libavdevice    56.  4.100 / 56.  4.100
  
  libavfilter     5. 40.101 /  5. 40.101
  
  libavresample   2.  1.  0 /  2.  1.  0
  
  libswscale      3.  1.101 /  3.  1.101
  
  libswresample   1.  2.101 /  1.  2.101
  
  libpostproc    53.  3.100 / 53.  3.100
  
  Output #0, mp3, to '/home/overtatech-1/Music/jeena.mp3':
  
  Output file #0 does not contain any stream

• Dealing with problems in FLAC audio files with ffmpeg

  15 janvier 2020, par Seamus

  I have gotten a set of FLAC (audio) files from a friend. I copied them to my Sonos music library, and got set to enjoy a nice album. Unfortunately, Sonos would not play the files. As a result I have been getting to know ffmpeg.

  Sonos’ complaint with the FLAC files was that it was "encoded at an unsupported sample rate". With rolling eyes and shaking head, I note that the free VLC media player happily plays these files, but the product I’ve paid for (Sonos) - does not. But I digress...

  ffprobe revealed that the FLAC files contain both an Audio channel and a Video channel :

  $ ffprobe -hide_banner  -show_streams "/path/to/Myaudio.flac"
  
  
  
  
  
      Duration: 00:02:23.17, start: 0.000000, bitrate: 6176 kb/s  
  
      Stream #0:0: Audio: flac, 176400 Hz, stereo, s32 (24 bit)  
  
      Stream #0:1: Video: mjpeg (Progressive), yuvj444p(pc, bt470bg/unknown/unknown), 450x446 [SAR 72:72 DAR 225:223], 90k tbr, 90k tbn, 90k tbc (attached pic)  
  
      Metadata:  
  
        comment         : Cover (front)  

  Cool ! I guess this is how some audio players are able to display the ’album artwork’ when they play a song ? Note also that the Audio stream is reported at 176400 Hz ! Apparently I’m out of touch ; I thought that 44.1khz sampling rate effectively removed all of the ’sampling artifacts’ we could hear. Anyway, I learned that Sonos would support a max of 48kHz sampling rate, and this (the 176.4kHz rate) is what Sonos was unhappy about. I used ffmpeg to ’dumb it down’ for them :

  $ ffmpeg -i "/path/to/Myaudio.flac" -sample_fmt s32 -ar 48000 "/path/to/Myaudio48K.flac"

  This seemed to work - at least I got a FLAC file that Sonos would play. However, I also got what looks like a warning of some sort :

  [swscaler @ 0x108e0d000] deprecated pixel format used, make sure you did set range correctly
  [flac @ 0x7feefd812a00] Frame rate very high for a muxer not efficiently supporting it.
  Please consider specifying a lower framerate, a different muxer or -vsync 2

  A bit more research turned up this answer which I don’t quite understand, and then in a comment says, "not to worry" - at least wrt the swscaler part of the warning.

  And that (finally) brings me to my questions :

  1.a. What framerate, muxer & other specifications make a graphic compatible with a majority of programs that use the graphic ?

  1.b. How should I use ffmpeg to modify the Video channel to set these specifications (ref. Q 1.a.) ?

  2.a. How do I remove the Video channel from the .flac audio file ?

  2.b. How do I add a Video channel into a .flac file ?

  EDIT :

  I asked the above (4) questions after failing to accomplish a ’direct’ conversion (a single ffmpeg command) from FLAC at 176.4 kHz to ALAC (.m4a) at 48 kHz (max supported by Sonos). I reasoned that an ’incremental’ approach through a series of conversions might get me there. With the advantage of hindsight, I now see I should have posted my original failed direct conversion incantation... we live and learn.

  That said, the accepted answer below meets my final objective to convert a FLAC file encoded at 176.4kHz to an ALAC (.m4a) at 48kHz, and preserve the cover art/video channel.