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• How to output fragmented mp4 with ffmpeg ?

  12 octobre 2016, par S B

  ffmpeg -i infile.avi out.mp4 outputs non-fragmented MP4.

  How do I obtain fragmented mp4 ?

  Update
  A fragmented mp4 file is internally divided into several back-to-back chunks or MPEG-4 movie fragments. Each chunk has its own moof atom - so there are several moof atoms interleaved in the file instead of a single moov at the end as in the case of an unfragmented mp4. This makes it easier to stream over slow networks where buffering is involved

  There are several tools like mp4box that convert a normal mp4 to a fragmented one. Unfortunately we cannot use something like this

  ffmpeg <options to="to" output="output" mp4="mp4"> | mp4box
  
  </options>

  since ffmpeg does not produce seekable output while producing mp4 containers.

• How to output fragmented mp4 with ffmpeg ?

  4 mars, par S B

  ffmpeg -i infile.avi out.mp4 outputs non-fragmented MP4.

  



  How do I obtain fragmented mp4 ?

  



  Update
A fragmented mp4 file is internally divided into several back-to-back chunks or MPEG-4 movie fragments. Each chunk has its own moof atom - so there are several moof atoms interleaved in the file instead of a single moov at the end as in the case of an unfragmented mp4. This makes it easier to stream over slow networks where buffering is involved

  



  There are several tools like mp4box that convert a normal mp4 to a fragmented one. Unfortunately we cannot use something like this

  



  ffmpeg <options to="to" output="output" mp4="mp4"> | mp4box&#xA;</options>

  



  since ffmpeg does not produce seekable output while producing mp4 containers.

  


• how to automatically oversample and downsample when using filters ?

  4 juin 2021, par Yue Wang

  I am researching avfilters. Say I have an audio with sample rate s, and bit depth d,

  


  What I want to do is to write a graph that

  


  

  • upsample s by 4x, and set precision to 64bit float

  


  • apply some biquad filters with 64bit precision

  


  • downsample by 4x back to s, and set bit depth back to d.

  


  


  The reason to oversample is to get better filtering result by antialiasing, and the reason to downsample is to stream using the original source format.

  


  I don't know if there's way that I can do it automatically in the graph.

  


  ashowinfo could print out the sample rate, but seems there's no way to use the value later in the pipeline.

  


  asoftclip has a oversample factor. but it's not available in other filters.