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• How to recover video from H264 frames and timestamps [closed]

  10 juin 2024, par kokosda

  My service receives H264 frames and some metadata related to them like Timestamp from MS Teams.

  


  Observations :

  


  

  • Those frames are inter-frame compressed.

  


  • Resolution of those frames can change.

  


  • Timestamps are like this one 39264692280552704. That represents year 125 if fed to .NET consturctor new DateTime(39264692280552704), so I need to add 1899 years to get a real date.

  


  • I can wrap the sequence to a playable mp4 container with ffmpeg -i input.h264 -c copy output.mp4, however it is not what I want because the resulting video plays too fast, like on fast forward. Thus, I would like those timestamps would be considered to recover a real timeline.

  


  


  I merged all the H264 frames in one file like input.h264 and saved all the timestamps in another file like metadata.json. In metadata.json, each object describes a single frame from input.h264.

  


  My question is how to recover the source video from frames and timestamps that I received from Teams ? Particularly, using FFMPEG.

  


• avr32 : remove explicit support

  9 juin 2024, par Rémi Denis-Courmont

  avr32 : remove explicit support
  The vendor has long since switched to Arm, with the last product
  
  reaching their official end-of-life over 11 years ago. Linux support for
  
  the ISA was dropped 7 years ago. More importantly, this architecture was
  
  never supported by upstream GCC, and the vendor fork is stuck at version
  
  4.2, which FFmpeg no longer supports (as per C11 requirement).
  Presumably, this is still the case given the lack of vendor support.
  
  Indeed all of the code being removed here consisted of inline assembler
  
  scalar optimisations. A sane C compiler should be able to perform those
  
  automatically nowadays (with the sole exception of fast CLZ detection),
  
  but this is moot as this architecture is evidently dead.
  

  • [DH] configure
  • [DH] libavcodec/avr32/mathops.h
  • [DH] libavcodec/mathops.h
  • [DH] libavutil/avr32/intreadwrite.h
  • [DH] libavutil/intreadwrite.h

• FFMPEG MKV -> MP4 Batch Conversion

  15 juillet 2024, par blaziken386

  I'm trying to write a program that lets me convert a series of .mkv files with subtitle files into .mp4 files with the subs hardcoded.

  


  Right now, the script I use is

  


  ffmpeg -i input.mkv -vf subtitles=input.mkv output.mp4



  


  This is fine, but it means I can only convert them one at a time, and it's kind of a hassle because it means I have to fiddle with it every few minutes to set up the next one.

  


  I have another script I use for converting .flac files to .mp3 files, which is

  


  @ECHO OFF

FOR %%f IN (*.flac) DO (
echo Converting: %%f
ffmpeg -i "%%f" -ab 320k -map_metadata 0 "%%~nf.mp3"
)

echo Finished

PAUSE



  


  Running that converts every single .flac folder into an .mp3 equivalent, with the same filename and everything.

  


  I've tried to combine the above scripts into something like this :

  


  @ECHO OFF

FOR %%f IN (*.mkv) DO (
echo Converting: %%f
ffmpeg -i "%%f" -vf subtitles=%%f "%%~nf.mp4"
)

echo Finished

PAUSE


  


  but every time I do so, it returns errors like "invalid argument" or "unable to find a suitable output type", or "error initializing filters", or "2 frames left in the queue on closing" or something along those lines. I've swapped out subtitles=%%f for "subtitles-%%f" or subtitles="%%f.mkv" and so on and so forth, and none of those give me what I want either. Sometimes it creates Empty .mp4 file containers with nothing in them, sometimes it does nothing at all.

  


  I don't really understand what exactly is happening under the hood in that flac->mp3 code, because I grabbed it from a different stackoverflow post years ago. All I know is that trying to copy that code and repurpose it into something else doesn't work. Is this just an issue where I've fucked up the formatting of the code and not realized it, or is this a "ffmpeg can't actually do that because of a weird technical issue" thing ?

  


  I also tried the code listed here, when Stackoverflow listed that as a possible duplicate, but that gave me similar errors, and I don't really understand why !

  


  Also, if it's relevant, I'm running windows.