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• configure : Include quotes around pkg_version

  16 décembre 2024, par Joe Schiffler

  configure : Include quotes around pkg_version
  In some MSYS environments it can happen that the 3 argument syntax
  
  for pkg-config library specifications fails because somehow the
  
  expansion of pkg_version ends up with a redirection we guess.
  To avoid failures like in the referenced build[2], we quote it
  
  so the whole module including operators will be expanded into
  
  a single shell word and the single argument syntax for specifying
  
  the library for pkg-config will be used.
  The single argument syntax seems to be supported by the original
  
  pkg-config from the beginning more than 20 years[3].
  In the pkgconf implementation single argument syntax was supported
  
  pretty much from the beginning as well. The multiple argument syntax
  
  we used until this change, was not supported until a change[4] more
  
  than 10 years ago.
  References
  
  1. Build passing with quotes :
  
     https://github.com/JoeSchiff/pyav-ffmpeg/actions/runs/12358403929
  
  2. Build failing without quotes :
  
     https://github.com/JoeSchiff/pyav-ffmpeg/actions/runs/12360472377
  
  3. Earliest commit of the current pkg-config Git repo already mentions the single argument syntax :
  
     https://gitlab.freedesktop.org/pkg-config/pkg-config/-/commit/2ac96cbcc708d8945329fd1b2001386e1c895c64#124c0becfe68b1ef671f49ed2b9d24779ace126f_0_162
  
  4. pkgconf gets support for 3 argument syntax (pkgconf —exists liba = 1.2.3) :
  
     https://github.com/pkgconf/pkgconf/commit/793de6a06ca52fbfe906a269b5f2b2ba41739517
  Commit-message-by : Alexander Strasser <eclipse7@gmx.net>
  
  Signed-off-by : Joe Schiffler <joeschiffler3@gmail.com>
  
  Signed-off-by : Alexander Strasser <eclipse7@gmx.net>
  

  • [DH] configure

• Is Replacing Dynamic Resolution with scale_amf in FFmpeg Command a Good Direction ?

  21 novembre 2024, par fred

  I'm working on a Lua script for MPV that processes 360-degree videos using FFmpeg's v360 filter. The original command dynamically calculates the output resolution based on a res variable, like this :

  


  mp.command_native_async({
    "no-osd", "vf", "add", 
    string.format(
        "@vrrev:v360=%s:%s:reset_rot=1:in_stereo=%s:out_stereo=2d:
id_fov=%s:d_fov=%.3f:yaw=%.3f:pitch=%s:roll=%.3f:
w=%s*192.0:h=%.3f*108.0:h_flip=%s:interp=%s",
        in_flip, inputProjection, outputProjection, in_stereo, idfov, dfov, yaw, pitch, roll, res, res, h_flip, scaling
    )
}, updateComplete)


  


  Change Proposal :

  


  I am considering replacing the dynamic width and height calculations with a scale_amf filter to handle scaling more efficiently and leverage GPU acceleration. The updated command would look like this :

  


  mp.command_native_async({
    "no-osd", "vf", "add", 
    string.format(
        "@vrrev:v360=%s:%s:reset_rot=1:in_stereo=%s:out_stereo=2d:
id_fov=%s:d_fov=%.3f:yaw=%.3f:pitch=%s:roll=%.3f,
%sscale_amf=w=%.0f:h=%.0f",
        inputProjection, outputProjection, in_stereo, idfov, dfov, yaw, pitch, roll, in_flip, res * 192.0, res * 108.0
    )


  


  Hardware Specifications :

  


  I am using an AMD Ryzen 5 5600G, no display card, 16GB RAM, Windows 10.

  


  Questions :

  


  Is using scale_amf for scaling a good direction in terms of performance and efficiency ?
Are there any potential drawbacks to this approach that I should be aware of ?
How does using scale_amf compare to the original dynamic resolution method in terms of output quality and processing speed ?
}, updateComplete)

  


  Any insights or experiences with this change would be greatly appreciated !

  


• How to decode frames from MDAT atom extracted from mp4 video [closed]

  24 septembre 2024, par Gurinderbeer Singh

  I am new to video codecs and learning video file format specifications. I have read about QUICKTIME file format specifications from here, and MP4 file format (which is almost similar) from here. There are atoms such FTYPE, MOOV, MDAT etc. The MDAT atom contains actual audio and video data. The MOOV atom contains information about how to extract data from MDAT, it gives references to chunks (samples).

  



  I want to extract the video samples in MDAT atom from video file without using any tool such ffmpeg, or juggler etc. I can write my own code for this. The problem is, even if I can locate the video data (samples) in MDAT by using information from MOOV, these samples are compressed. And we need to uncompress these to get frames.
My question is can we uncompress the samples extracted from MDAT and get the actual video frames ?

  



  Tools such as xuggler, ffmpeg etc are used to extract frames from video files. 
But here I want to extract the samples(for video data) from MDAT by writing my own code, but then I want to uncompress those by using some tool. I don't want to write codecs.

  



  Can anyone please help me with this....!

  



  Thanks...