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• Are there any resources listing current codecs and formats not supported by FFmpeg ?

  4 mars 2020, par Alexander Swann

  We are building a service where we do not know what format/codec a video uploaded by a user is in. Due to the nature of the application, we expect input video formats to be very fragmented, diverse and niche. We are currently using FFmpeg to transcode input formats to a consistent output (e.g. mp4).

  Due to the above scenario, I would like to establish a general list of what formats and codecs are not currently supported by FFmpeg. This is so I can research other open source video transcoding tools which I can utilise to fill in the gaps and allow our service to be more reliable for the user.

  Are there resources online that can help at least get a general idea of what might not be supported by FFmpeg ?

• How to Speed Up Two-Pass Encoding ?

  27 juillet 2017, par Matt McManis

  I have a Video file with Audio, Subtitles, Chapters, and Metadata.

  I removed Audio and Subtitles with -an -sn from -pass 1 and then inlclude them in -pass 2.

  What about for Chapters and Metadata ? And how do you apply Turbo to -pass 1 ?

  Is there anything more that can be done ?

  ---

  I have a script that will convert mpg to mp4. I’ve sorted it with linebreaks so it’s easier to read.

  Pass 1

  "C:\Videos\example.mpg" 
  
  
  
  -vcodec libx264 
  
  -preset medium -b:v 2500K -pix_fmt yuv420p -qcomp 0.8 
  
  -vf scale="trunc(iw/2)*2:trunc(ih/2)*2" 
  
  -pass 1 
  
  
  
  -map 0:v:0? -an -sn
  
  
  
  -threads 8 
  
  
  
  "C:\Videos\example.mp4" 

  Pass 2

  ffmpeg -y -i 
  
  
  
  "C:\Videos\example.mpg" 
  
  
  
  -vcodec libx264 
  
  -preset medium -b:v 2500K -pix_fmt yuv420p -qcomp 0.8 
  
  -vf scale="trunc(iw/2)*2:trunc(ih/2)*2" 
  
  -pass 2 
  
  
  
  -acodec aac 
  
  -b:a 320k 
  
  -af volume=1.2 
  
  
  
  -map 0:v:0? -map 0:a:0? -map 0:s? -c:s copy -map_metadata 0 
  
  
  
  -threads 8 
  
  
  
  "C:\Videos\example.mp4"

• Decoding to specific pixel format in ffmpeg with C++

  26 juillet 2019, par Lucas Zanella

  I need to decode video but my video player only supports RGB8 pixel format. So I’m looking into how to do pixel format conversion in the GPU, preferably in the decoding process, but if not possible, after it.

  I’ve found How to set decode pixel format in libavcodec ? which explains how to decode video on ffmpeg to an specific pixel format, as long as it’s suported by the codec.

  Basically, get_format() is a function which chooses, from a list of supported pixel formats from the codec, a pixel format for the decoded video. My questions are :

  1. Is this list of supported codec output formats the same for all computers ? For example, if my codec is for H264, then it will always give me the same list on all computers ? (assuming same ffmpeg version of all computers)
  2. If I choose any of these supported pixel formats, will the pixel format conversion always happen in the GPU ?
  3. If some of the pixel format conversions won’t happen in the GPU, then my question is : does sws_scale() function converts in the GPU or CPU ?