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• AVCodecContext::channel_layout 0 for WAV files

  30 décembre 2013, par cmannett85

  I have been successfully loading compressed audio files using FFmpeg and querying their channel_layouts using some code I've written :

  AVFormatContext* fmtCxt = nullptr;
  
  avformat_open_input( &fmtCxt, "###/440_sine.wav", nullptr, nullptr );
  
  avformat_find_stream_info( fmtCxt, nullptr );
  
  av_find_best_stream( fmtCxt, AVMEDIA_TYPE_AUDIO, -1, -1, nullptr, 0 );
  
  
  
  AVCodecContext* codecCxt = fmtCxt->streams[ret]->codec;
  
  AVCodec* codec = avcodec_find_decoder( codecCxt->codec_id );
  
  avcodec_open2( codecCxt, codec, nullptr );
  
  
  
  std::cout << "Channel Layout: " << codecCxt->channel_layout << std::endl;
  
  av_dump_format( fmtCxt, 0, "###/440_sine.wav", 0 );

  I've removed all error checking for brevity. However for Microsoft WAV files (mono or stereo) the AVCodecContext::channel_layout member is always 0 - despite ffprobe and av_dump_format(..) both returning valid information :

  Input #0, wav, from '###/440_sine.wav':
  
  Duration: 00:00:00.01, bitrate: 740 kb/s
  
  Stream #0:0: Audio: pcm_s16le ([1][0][0][0] / 0x0001), 44100 Hz, 1 channels, s16, 705 kb/s

  Also codecCxt->channels returns the correct value. Using a flac file (with exactly the same audio data generated from the same application), gives a channel_layout of 0x4 (AV_CH_FRONT_CENTER).

• AVCodecContext::channel_layout 0 for WAV files

  25 novembre 2020, par cmannett85

  I have been successfully loading compressed audio files using FFmpeg and querying their channel_layouts using some code I've written :

  



  AVFormatContext* fmtCxt = nullptr;
avformat_open_input( &fmtCxt, "###/440_sine.wav", nullptr, nullptr );
avformat_find_stream_info( fmtCxt, nullptr );
av_find_best_stream( fmtCxt, AVMEDIA_TYPE_AUDIO, -1, -1, nullptr, 0 );

AVCodecContext* codecCxt = fmtCxt->streams[ret]->codec;
AVCodec* codec = avcodec_find_decoder( codecCxt->codec_id );
avcodec_open2( codecCxt, codec, nullptr );

std::cout << "Channel Layout: " << codecCxt->channel_layout << std::endl;
av_dump_format( fmtCxt, 0, "###/440_sine.wav", 0 );


  



  I've removed all error checking for brevity. However for Microsoft WAV files (mono or stereo) the AVCodecContext::channel_layout member is always 0 - despite ffprobe and av_dump_format(..) both returning valid information :

  



  Input #0, wav, from '###/440_sine.wav':
Duration: 00:00:00.01, bitrate: 740 kb/s
Stream #0:0: Audio: pcm_s16le ([1][0][0][0] / 0x0001), 44100 Hz, 1 channels, s16, 705 kb/s


  



  Also codecCxt->channels returns the correct value. Using a flac file (with exactly the same audio data generated from the same application), gives a channel_layout of 0x4 (AV_CH_FRONT_CENTER).

  


• Use ffmpeg to stream live content to azure media services

  9 juin 2016, par Dadicool

  I’ve been trying to stream content to azure media services using ffmpeg as it’s one of the options described here : http://azure.microsoft.com/blog/2014/09/18/azure-media-services-rtmp-support-and-live-encoders/

  My command is :

  ffmpeg -v verbose -i 300.mp4 -strict -2 -c:a aac -b:a 128k -ar 44100 -r 30 -g 60 -keyint_min 60 -b:v 400000 -c:v libx264 -preset medium -bufsize 400k -maxrate 400k -f flv rtmp://nessma-****.channel.mediaservices.windows.net:1935/live/584c99f5c47f424d9e83ac95364331e7

  I have made sure that the streaming endpoint has one active streaming unit, I also made sure that the channel is actually Ready and I even get it to start streaming (which makes a PublishURL available).

  When I execute the ffmpeg command to start streaming, I keep getting the following error :

  ffmpeg version 2.5.2 Copyright (c) 2000-2014 the FFmpeg developers
 built on Dec 30 2014 11:31:18 with llvm-gcc 4.2.1 (LLVM build 2336.11.00)
 configuration: --prefix=/Volumes/Ramdisk/sw --enable-gpl --enable-pthreads --enable-version3 --enable-libspeex --enable-libvpx --disable-decoder=libvpx --enable-libmp3lame --enable-libtheora --enable-libvorbis --enable-libx264 --enable-avfilter --enable-libopencore_amrwb --enable-libopencore_amrnb --enable-filters --enable-libgsm --enable-libvidstab --enable-libx265 --arch=x86_64 --enable-runtime-cpudetect
 libavutil      54. 15.100 / 54. 15.100
 libavcodec     56. 13.100 / 56. 13.100
 libavformat    56. 15.102 / 56. 15.102
 libavdevice    56.  3.100 / 56.  3.100
 libavfilter     5.  2.103 /  5.  2.103
 libswscale      3.  1.101 /  3.  1.101
 libswresample   1.  1.100 /  1.  1.100
 libpostproc    53.  3.100 / 53.  3.100
Routing option strict to both codec and muxer layer
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x7f9a0a002c00] overread end of atom 'colr' by 1 bytes
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x7f9a0a002c00] stream 0, timescale not set
[mov,mp4,m4a,3gp,3g2,mj2 @ 0x7f9a0a002c00] max_analyze_duration 5000000 reached at 5003637 microseconds
Input #0, mov,mp4,m4a,3gp,3g2,mj2, from '300.mp4':
 Metadata:
   major_brand     : mp42
   minor_version   : 0
   compatible_brands: mp42isomavc1
   creation_time   : 2014-01-11 05:39:32
   genre           : Trailer
   artist          : Warner Bros.
   title           : 300: Rise of an Empire - Trailer 2
   encoder         : HandBrake 0.9.9 2013051800
   date            : 2014
 Duration: 00:02:33.24, start: 0.000000, bitrate: 7377 kb/s
   Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p(tv, bt709), 1920x1080 (1920x1088), 7219 kb/s, 23.98 fps, 23.98 tbr, 90k tbn, 47.95 tbc (default)
   Metadata:
     creation_time   : 2014-01-11 05:39:32
     encoder         : JVT/AVC Coding
   Stream #0:1(eng): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, stereo, fltp, 157 kb/s (default)
   Metadata:
     creation_time   : 2014-01-11 05:39:32
   Stream #0:2: Video: mjpeg, yuvj420p(pc, bt470bg/unknown/unknown), 101x150 [SAR 72:72 DAR 101:150], 90k tbr, 90k tbn, 90k tbc
rtmp://nessma-****.channel.mediaservices.windows.net:1935/live/584c99f5c47f424d9e83ac95364331e7: Input/output error

  The Azure blog post clearly states that this should be possible but I can’t find a working example anywhere.

  Environment :

  • MacOS Maverick
  • FFMPEG installed from official build
  • 300.mp4 : 1080p trailer of the latest 300 movie