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• How to utilize hardware decode for audio ?

  20 mars 2014, par jAckOdE

  I have a buffer that contain packets read by ffmpeg from a video file encoded using H264/AAC
  According to Apple document, audio stream encoded in AAC can be decode with hardware support,

  how to decode the audio stream with hardware support ?

  UPDATE : I use Audio Queue Service to output the audio. Right now i decode AAC packet using ffmpeg and send LPCM audio to AQS. According to the Apple document, I can send directly AAC audio to AQ and it will take care of decoding task. Does it decode with hardware ? Do i need, and how to set Audio Queue's parameter to enable audio hardware decoding ?

• In what way does this HEVC video not comply to Apples's requirements document ?

  16 novembre 2022, par Duke Dougal

  My goal is to work out why a given video file does not play on Macos/Safari/Quicktime.

  


  The background to this question is that it is possible to play HEVC videos with a transparent background/alpha channel on Safari/MacOS. To be playable, a video must meet the specific requirements set out by Apple in this document :

  


  https://developer.apple.com/av-foundation/HEVC-Video-with-Alpha-Interoperability-Profile.pdf

  


  The video that does not play on Apple/Safari/Quicktime is an HEVC video with an alpha transparency channel. Note that VLC for MacOS DOES play this file. Here it is :

  


  https://drive.google.com/file/d/1ZnXjcDbk-_YxTgRuH_D7RSR9SXdY_XTv/view?usp=share_link

  


  I have two example HEVC video files with a transparent background/alpha channel, and they both play fine using either Quicktime player or Safari :

  


  Working video #1 :

  


  https://drive.google.com/file/d/1PJAyg_sVKVvb-Py8PAu42c1qm8l2qCbh/view?usp=share_link

  


  Working video #2 :

  


  https://drive.google.com/file/d/1kk8ssUyT7qAaK15afp8VPR6mIWPFX8vQ/view?usp=sharing

  


  The first step is to work out in what way my non-working video ( https://drive.google.com/file/d/1ZnXjcDbk-_YxTgRuH_D7RSR9SXdY_XTv/view?usp=share_link ) does not comply with the specification.

  


  Once it is clear which requirements are not met by the non-working video then I can move onto the next phase, which is to try to formulate an ffmpeg command that will output a video meeting the requirements.

  


  I have read Apples requirements document and I am out of my depth in trying to analyse the non working video against the requirements - I don't know how to do it.

  


  Can anyone suggest a way to identify what is wrong with the video ?

  


  Additional context is that I am trying to find a way to create Apple/MacOS compatible alpha channel / transparent videos using ffmpeg with hevc_nvenc running on an Intel machine. I am aware that Apple hardware can create such videos, but for a wide variety of reasons it is not practical for me to use Apple hardware to do the job. I have spent many hours trying all sorts of ffmpeg and ffprobe commands to try to work out what is wrong and modify the video to fix it, but to be honest most of my attempts are guesswork.

  


• FFMPEG iPhone using gas-preprocessor

  5 mars 2012, par user308990

  I got the latest version of FFMPEG and gas-preprocessor, and i am trying to build them libraries for iPhone. I put the gas-preprocessor.pl file in my usr/bin folder, and try to configure my ffmpeg with this command.

  ./configure —cc=/Developer/Platforms/iPhoneOS.platform/Developer/usr/bin/arm-apple-darwin9-gcc-4.2.1 —as='gas-preprocessor.pl /Developer/Platforms/iPhoneOS.platform/Developer/usr/bin/arm-apple-darwin9-gcc-4.2.1' —sysroot=/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS3.1.sdk —enable-cross-compile —target-os=darwin —arch=arm —cpu=cortex-a8 —enable-pic

  But what i get is this error

  Unknown option "—as=gas-preprocessor.pl".
  See ./configure —help for available options.

  Any ideas ??? Thank u.