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• Revision 7e515c4637 : fix AVX & AVX2 detection fixes issue #790 which resulted in a SIGILL on OpenBSD

  15 janvier 2015, par James Zern

  Changed Paths :
   Modify /vpx_ports/x86.h

  
  
  fix AVX & AVX2 detection

  fixes issue #790 which resulted in a SIGILL on OpenBSD

  code is mostly from libwebp, based on the following :

  https://software.intel.com/en-us/articles/how-to-detect-new-instruction-support-
  in-the-4th-generation-intel-core-processor-family

  Change-Id : Ida7c1a18261e98c05ed9c662068140be407ec107

• Can this be done in Handbrake or FFMPEG

  2 décembre 2022, par Takin

  Just wonder this could be done in Handbrake or FFMPEG.
Any other transcoding software in Windows or MacOS would also be acceptable.

  



  I have many family videos, shooted with DSLR/action cam/phone.
And the files are really huge without transcoding them.
There are something I would like to have,

  



  


  1. Metadata should be all captured. Using Handbrake would not be able to capture the information of the used device. Also, the capture date will become the transcoding date which is definitely unacceptable.

  


  2. I would like to transcode them into HEVC (H.265)

  


  3. I need to batch transcode them since there're a lot of videos.

  


  



  If it's possible (not neccessary), I would also like to have the filename as "YYYYMMDD_HHMMSS".

  



  I think both 1 and 3 are quite frequently asked questions.
This thread will be quite useful to all people who are looking for the same answer as well.
Thanks a lot !

  


• Transcode HLS Segments individually using FFMPEG

  27 mai 2013, par rayh

  I am recording a continuous, live stream to a high-bitrate HLS stream. I then want to asynchronously transcode this to different formats/bitrates. I have this working, mostly, except audio artefacts are appearing between each segment (gaps and pops).

  Here is an example ffmpeg command line :

  ffmpeg -threads 1 -nostdin -loglevel verbose \
  
     -nostdin -y -i input.ts -c:a libfdk_aac \
  
     -ac 2 -b:a 64k -y -metadata -vn output.ts

  Inspecting an example sound file shows that there is a gap at the end of the audio :

  

  And the start of the file looks suspiciously attenuated (although this may not be an issue) :

  

  My suspicion is that these artefacts are happening because transcoding are occurring without the context of the stream as a whole.

  Any ideas on how to convince FFMPEG to produce audio that will fit back into a HLS stream ?

  ** UPDATE 1 **

  Here are the start/end of the original segment. As you can see, the start still appears the same, but the end is cleanly ended at 30s. I expect some degree of padding with lossy encoding, but I there is some way that HLS manages to do gapless playback (is this related to iTunes method with custom metadata ?)

  
  

  ** UPDATED 2 **

  So, I converted both the original (128k aac in MPEG2 TS) and the transcoded (64k aac in aac/adts container) to WAV and put the two side-by-side. This is the result :

  
  

  I'm not sure if this is representative of how a client will play it back, but it seems a bit odd that decoding the transcoded one introduces a gap at the start and makes the segment longer. Given they are both lossy encoding, I would have expected padding to be equally present in both (if at all).

  ** UPDATE 3 **

  According to http://en.wikipedia.org/wiki/Gapless_playback - Only a handful of encoders support gapless - for MP3, I've switched to lame in ffmpeg, and the problem, so far, appears to have gone.

  For AAC (see http://en.wikipedia.org/wiki/FAAC), I have tried libfaac (as opposed to libfdk_aac) and it also seems to produce gapless audio. However, the quality of the latter isn't that great and I'd rather use libfdk_aac is possible.