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• How to split 5.1 audio into discrete AAC streams in FFmpeg 4.0

  17 décembre 2018, par OwlBoy

  Up until FFmpeg v4.0 I have been able to run the following command on an input video file that contains an H.264 video track and either AC3 or DTS audio stream and produce an MP4 that has 6 streams of audio. Each stream corresponds to a channel of the 5.1 audio.

  ffmpeg -i INPUT.MKV -vcodec copy -filter_complex channelsplit=channel_layout=5.1 -acodec aac -movflags faststart OUTPUT.MP4

  It even worked on Stereo tracks and put the L and R channels into the proper places and produced some extraneous silent tracks for the other 4 channels.

  But now in v4.0.1 I get the following error :

  [aac @ 0x7f7f65001e00] Unsupported channel layout

  Error initializing output stream 0:0 — Error while opening encoder for output stream #0:0 - maybe incorrect parameters such as bit_rate, rate, width or height

  Conversion failed !

  Changing the command to be the following does not improve things :

  ffmpeg -i INPUT.MKV -vcodec copy -filter_complex "channelsplit=channel_layout=5.1[FL][FR][FC][LFE][BL][BR]" -acodec aac -movflags faststart OUTPUT.MP4

  It gives the following error :

  Filter channelsplit:BR has an unconnected output

  (Note that BL/BR and SL/SR both produce the same error about BR)

  This MP4 file structure is useful for playing back inside of Unity with virtual speakers placed in the environment.

  My end goal :

  - MP4 (MOOV Atom at the Front)
  
      -H.264 Video Stream
  
      -AAC Audio Stream - FL
  
      -AAC Audio Stream - FR
  
      -AAC Audio Stream - FC
  
      -AAC Audio Stream - LFE
  
      -AAC Audio Stream - SL
  
      -AAC Audio Stream - SR

• avcodec/hevcdec : check ff_init_cabac_decoder() for failure

  24 juin 2017, par Michael Niedermayer

  avcodec/hevcdec : check ff_init_cabac_decoder() for failure
  Fixes : runtime error : left shift of 1965559808 by 4 places cannot be represented in type 'int'
  
  Fixes : 2333/clusterfuzz-testcase-minimized-5223935677300736
  Found-by : continuous fuzzing process https://github.com/google/oss-fuzz/tree/master/projects/ffmpeg
  
  Reviewed-by : Paul B Mahol <onemda@gmail.com>
  
  Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] libavcodec/hevc_cabac.c
  • [DH] libavcodec/hevcdec.c
  • [DH] libavcodec/hevcdec.h

• Using OpenMAX (IL ?) for audio/video decoding on Android

  14 septembre 2012, par Christopher Corsi

  Many of the newer hardware platforms running Android, in particular NVIDIA's Tegra 2, support OpenMAX for media acceleration. It's effectively impossible on today's devices to decode 720p video without this support, but the number of demuxers supported on Android are quite slim. The only public API I've been able to find has been through the MediaPlayer class in the Android SDK. There are multiple places in the Android source tree with OpenMAX related tidbits, however.

  On my device (Samsung Galaxy Tab 10.1) I've got access to hardware decoders through a multitude of OpenMAX libs in /system/lib, and it would be great to interface my video application with these. Can anyone point me to information on implementing a decoder powered by OpenMAX ? I've found the documentation from Khronos, but nothing in the way of example code or tutorials. I've already got demuxing and even software decoding taken care of (via libavcodec/libavformat), I'd just like to put hooks in to enable hardware encoding. I'm also assuming here it would be necessary to link directly to the ones available on the device, which makes it pretty lackluster in terms of portability, but it works.

  Alternatively, I'm interested in anything anyone knows about private APIs for accessing the video decoding available on Tegra 2 devices. Especially if there's a vdpau interface like what NVIDIA implements for desktop linux distributions, since there's plenty available for that - but I wasn't able to find shared libraries that indicate that support.