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• Absolute timestamp as MP4 start time

  14 juin 2016, par galbarm

  I’d like to store the exact start time a video was recorded on, inside its mp4 container.
  I need a millisecond accuracy (i.e. year,month,day,hour,sec,milli).
  Such an accuracy requires 8 bytes.

  The only standard way I found to store a video creation time is to use the mvhd/tkhd/mdhd boxes creation_time field.
  But according to the base media file format spec, the field only gives a granularity of seconds :

  creation_time is an integer that declares the creation time of this
  track (in seconds since midnight, Jan. 1, 1904, in UTC time)

  In version 0 the field size was 4 bytes, while in version 1 it was increased to 8 bytes. But the description remained unchanged so it can still only reflect a timestamp in up to second granularity. (for maintaining backward compatibility maybe ?)

  So finally, is there a standard way to store a single absolute timestamp with millisecond accuracy in a mp4 container ?
  If the only way to do it, is to store it as a custom metadata, is there an agreed common way to do it according to ?

• where can one find old patches/curated versions of ffmpeg for qsv (mpeg2_qsv) ?

  10 avril 2023, par CodeCalf

  for the past year or so the mpeg2_qsv encoder in ffmpeg/libmfx has been broken due to a idr interval problem (sends only one idr frame at the start of the video rather than sending idr frames at a certain interval) i have found a solution/workaround by adding the idr-interval option defined in h264_qsv.c to the mpeg2_qsv.c provided in ffmpeg it does work but the quality of the output is subpar even after applying heavy post processing filters and i have been working on this exact platform for the past 4 years so i know for a fact that it used to work way better hence i have been trying to revert the changes made to ffmpeg in the past 1-2 years unsuccessfully as i am not able to find old patches that i could use as reference.

  


  i understand that for this problem a lot of people suggest using ffmpeg 2.8 which apparently is the best for old qsv behaviour but due to mediasdk version mismatches i haven't been able to build it successfully on any new OS after ubuntu 18.04 but i cannot use ubuntu 18.04 or below because of a hardware issue on my platform which messes with the xserver introducing a lot of weird errors if anyone has any suggestions of how i can overcome this then please help as i am all ears

  


  i am new to this website so i apologize in advance if i have made a mistake in asking this question.

  


  thank you for your patience and guidance

  


• 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.