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• x86 : Don’t use explicitly aligned versions of SAD on AVX CPUs

  3 mai 2013, par Henrik Gramner

  x86 : Don’t use explicitly aligned versions of SAD on AVX CPUs
  On modern CPUs movdqu isn’t slower than movdqa when used on aligned data and using the same code in both cases saves cache.
  This was already done for the high bit-depth AVX2 implementation but the aligned version still exists as dead code so remove that.
  

  • [DH] common/pixel.c
  • [DH] common/x86/pixel.h
  • [DH] common/x86/sad16-a.asm

• ffmpeg errors out with Error initializing output stream 0:0 for the setting `-profile:v main`

  17 octobre 2020, par Vishwasa Navada K

  We are using ffmpeg for generating HSL streaming files (.m3u8, .ts) from multiple type of input video and audio like avi, mp4, mp3, mkv, m4a etc. We are trying to encode everything into h264 streams to support modern browsers. But we are facing issues in converting few videos of type avi and mp4 (not all). Below is the ffmpeg command (it's using ffmpeg fluent on NodeJS).

  


  ffmpeg(fileName)
  .outputOptions([
    '-c:v h264',
    '-profile:v main',
    `-vf scale=1280:-2`,
    '-hls_list_size 0',
    '-start_number 0',
    '-hls_time 10',
    '-loglevel error',
  ])
  .output(output_file_path)


  


  When we try to run this with some set of specific avi and mp4 samples, it errors out saying
Error: ffmpeg exited with code 1: Error initializing output stream 0:0 -- Error while opening encoder for output stream #0:0 - maybe incorrect parameters such as bit_rate, rate, width or height.

  


  I tried changing few commands (like providing crf value) and tried to run them, The only time it successfully converted converted them was when I removed the output option -profile:v main. I am not sure about the reason behind it.

  


  I ran ffprobe to get the information from the videos that were not able to generate streams. I have them uploaded to gist here : https://gist.github.com/vishwasnavadak/91b5c978e2a3cb7a7c7a2bb505487263

  


  Is there something I am missing ? What is the reason for it to error out when -profile:v main option is present ?

  


• How to work with data from streaming services in my Java application ?

  24 novembre 2020, par gabriel garcia

  I'm currently trying to develop an "streaming client" as a way to organize multiple stream services (twitch, yt, mitele...) in a single desktop application written in Java.

  


  It basically relies on streamlink (which relies in ffmpeg) thanks to all it's features so my project could be defined as a frontend for streamlink.

  


  Straight to the point, one of the features I'd like to add it is the option to programatically record streams in the background and showing this video stream to the user when it's requested. Since there's also the possibility that the user wants to watch the stream without recording it, I'm forced to work with all that byte-like data sent from those streaming sources.

  


  So, the problem is basically that I do not know much about video coding/decoding/muxing/demuxing nor video theory like container structure, video formats and such.

  


  But the idea is to work with all the data sent from the stream source (let's say twitch, for example), read this bytes (I'm not sure what kind of information is sent to the client nor format) from the java.lang.Process's stdout and then present it to the client.

  


  Here's another problem : I don't know how to play video streams in JavaFX and I don't think it's even supported right now. So I would have to extract each frame and sound associated from the stdout and show them to the user each time a new frame is received (oups, another problem since I don't know when does each frame starts/ends since I'm reading each stdout's line).

  


  As a summary :

  


  

  • How can I know when does each frame starts/stops ?

  


  • How can I extract the image and sound from each frame ?

  


  


  I hope I'm not asking too much and that you could shed some light upon my darkness.