Recherche avancée

Sur d’autres sites (10929)

• Set RTSP/UDP buffer size in FFmpeg/LibAV

  9 décembre 2016, par chuckleplant

  Note : I’m aware ffmpeg and libav are different libraries. This is a problem common to both.

  Disclaimer : Duplicate of SO question marked as answered but actually didn’t give a proper solution.

  ---

  Insufficient UDP buffer size causes broken streams for several high resolution video streams. In LibAV/FFMPEG it’s possible to set the udp buffer size for udp urls (udp ://...) by appending some options (buffer_size) to it.

  However, for RTSP urls this is not supported.

  These are the only solutions I’ve found :

  • Rebuilding ffmpeg/libav changing the UDP_MAX_PKT_SIZE in the udp.c source file.
  • Using a nasty hack to find and modify the required value, by casting some private structs.
  • Using a different decoding library (proposed solution to aforementioned related SO question).

  None of these is actually a solution. From what I found it should be possible to use the API’s AVOptions to find and set this value. Or else, the AVDictionary.

  It’s very difficult to find how to set these throughout the documentation of either libav or ffmpeg.

  Update :

  The following patches have been submited to Libav tackling this topic, thanks to Libav developer @lu_zero :

  • Add a buffer_size option
  • Map the urloptions to AVOptions

  Which should offer a hint on how to implement those, still these are not yet available through the official stable API.

• How to convert VP8 track with different frame resolution to h264

  13 septembre 2016, par Nikita

  I have a .webm file with VP8 track, recorded from WebRTC stream by external service (TokBox Archiving). The stream is adaptive, so each frame in track could have different resolution. Most players (in webkit browsers) use video resolution from track description (which is always 640x480) and scale frames to this resolution. Firefox and VLC player uses real frame resolution, changing video resolution respectively.

  I want to achieve 2 goals :

  1. play this video in Internet Explorer 9+ without additional plugin installation.
  2. change frames resolution to one fixed resolution, so the video will look identically in different browsers.

  So, my plan is :

  • extract frames from source webm file to images with real frame resolution (e.g. PNG or BMP) (how could I do that ?)
  • find max width and max height of images
  • add black padding to images, so smaller frames will be in the center of a new frame (of size MAX_WIDHTxMAX_HEIGHT)
  • combine images to h264 track using ffmpeg

  Is all correct ? How can I achieve this ? Can this algorithm be optimized some way ?

  I tried ffmpeg to extract images, but it does not parse real frame resolution, using resolution from track header.
  I think some libwebm functions can help me (to parse frame headers and extract images). Maybe someone has some code snippets to do this ?

  Example .webm (download source, do not play google-converted version) : https://drive.google.com/file/d/0BwFZRvYNn9CKcndhMzlVa0psX00/view?usp=sharing

  Official description of adaptive stream from TokBox support : https://support.tokbox.com/hc/en-us/community/posts/206241666-Archived-video-resolution-is-supposed-to-be-720x1280-but-reports-as-640x480

• libavcodec/amfenc : Vulkan initialization support for encoder.

  8 août 2019, par OvchinnikovDmitrii

  libavcodec/amfenc : Vulkan initialization support for encoder.
  Added linux support for amf encoder through vulkan.
  To use h.264(AMD VCE) encoder on linux amdgru-pro version 19.20+ and
  
  amf-amdgpu-pro package(amdgru-pro contains, but does not install
  
  automatically) are required.
  This driver can be installed using amdgpu-pro-install script in
  
  official amd driver archive.
  Initialization of amf encoder occurs in this order :
  
  1) trying to initialize through dx11(only windows)
  
  2) trying to initialize through dx9(only windows)
  
  3) trying to initialize through vulkan
  Only Vulkan initialization available on linux.
  

  • [DH] Changelog
  • [DH] doc/general.texi
  • [DH] libavcodec/amfenc.c
  • [DH] libavcodec/version.h