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• dts to m4a (aac) ffmpeg to qaac output issue

  10 avril 2014, par user8979

  Looking to encode 2 dts 5.1 audio sources (Sonic Landscape and The Digital Experience) to m4a (aac) 5.1 with qaac 2.35. Input piped to qaac using :

  ffmpeg -report -loglevel verbose -i "input.file" -vn -f wav -codec:a pcm_f32le - | qaac --cvbr 160 --quality 2 --rate=keep --ignorelength --no-delay - -o "output.m4a"

  • Sonic Landscape duration : 18.848s, qaac output duration : 18.859s

    • output .m4a duration mismatch
    • mediainfo reports output is 2ch while mediatab and ffmpeg report output is 5.1ch (lfe)
      
      

  • The Digital Experience duration : 32.875s, qaac output duration : 32.875s

    • mediainfo reports output is 2ch while mediatab and ffmpeg report output is 5.1ch (lfe)
      
      

  1. what caused the duration mismatch in the first one ? how can it be fixed ?
  2. is the output 2ch or 5.1ch ?
     
     • if it is 2ch, what qaac option(s) leave the channels in output same as input ?
     • if the output is 5.1ch, does qaac then always preserve channels unless explicitly told otherwise ?

• FFmpeg and choice right windows configuration- CPU, memory and GPU

  28 septembre 2020, par ekvador

  I have windows PC, 16 gb memory, intel i7 920/ 2.67 GHz and on this machine running several apps, and ffmpeg for converting videos, it is usage for one day :

  


  CPU and memory usage

  


  When ffmpeg working , usage for CPU is 100, it working about 1,5 hour by day .

  


  Question is, what FFmpeg using for work is this CPU only or and GPU, if I want to increase FFmpeg jobs , do I need stronger PC ? thanks

  


• Is there a set of working P/Invoke declarations for FFMpeg, libavutil, libavformat and libavcodec in .NET ?

  11 février 2014, par casperOne

  I'm currently looking to access libavutil, libavformat and libavcodec (all part of FFMpeg) from .NET.

  Currently, I'm getting the libraries from the automated builds of the shared FFMpeg package performed every night for Windows 32-bit.

  I am also using the code from the ffmpeg-sharp project. In that project, I have removed a number of classes that were not compiling (they are wrapper classes not the P/Invoke declarations).

  The code compiles fine, but I am running into a few issues.

  First, it appears that the build of av*.dll uses the cdecl calling convention, as I was receiving a number of PInvokeStackImbalanceException when trying to call av_open_input_file. This was easy enough to change to get it to work right. The AVFormatContext structure is populated.

  After that, I want to call av_find_stream_info to get information about the streams in the file. However, when calling that with the AVFormatContext retrieved from the call to av_open_input_file, an AccessViolationException is thrown indicating that I am trying to read or write from protected memory.

  Has anyone used P/Invoke to access the libavutil, libavformat and libavcodec dll libraries through P/Invoke and have gotten it to work ?

  I should mention that working with the command-line version of FFMpeg, while a solution, is not a viable solution in this case, access needs to occur through the libraries. The reason for this is that I'd have to thrash the disk way too much to do what I need to do (I have to do a frame-by-frame analysis of some very high definition video) and I want to avoid the disk as much as possible.