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• How do I set the first and last frame of a video to be an image ?

  16 septembre 2011, par user205865

  HTML 5 implementations are different across various browsers. In firefox, the image specified by the placeholder attribute will be shown until the user clicks play on the video. In chrome, the placeholder image is shown until the video is loaded (not played), at which point the first frame of the video is shown.

  To reconcile this issue, I would like to set the first frame of the video to the placeholder image so that the experience will be the same in both browsers.

  I would preferably do this using ffmpeg or mencoder. I have very limited experience using these however, so if someone could point me in the right direction, I would be much obliged.

  Thanks !

• avcodec/ac3enc_template : Perform compile-time checks at compile-time

  3 décembre 2020, par Andreas Rheinhardt

  avcodec/ac3enc_template : Perform compile-time checks at compile-time
  Runtime checks for whether the encoder is fixed-point or not are
  
  unnecessary here as this is a template ; furthermore, there is no
  
  fixed-point EAC-3 encoder, so some checks for whether one is in EAC-3
  
  mode can be omitted when doing fixed-point encoding.
  Signed-off-by : Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
  

  • [DH] libavcodec/ac3enc_template.c

• FFMPEG split audio files accurately

  5 mai 2015, par Jakob Hougaard Andersen

  I am trying to use ffmpeg to split uncompressed audio files. I would like to split them very precisely at certain points.
  My experiments so far have led me to this procedure :

  ffmpeg -ss 1.126 -i someInputFile.wav -acodec copy -t 0.634 someOutputFile.wav

  So I am seeking (-ss) to a certain point in the input file and then I am outputting to a file with a defined length (-t).

  The -ss parameter seems to locate the starting point very accurately, but the length of the file doesn’t seem to match my defined length exactly.
  It seems that the file size jumps in steps of 4096 bytes (and the length with it) so that I can not define a file length in between two steps.

  I know that 4096 bytes is not a lot, but for a mono wave file (44.1kHz, 16 bit) it equals a step size of approximately 45 ms. I would really like to be able to define the length as precisely as the starting point.

  So my question is : is it possible to avoid this 4096 byte quatization on the output file length ?

  I have tried to use the ’chomp’ bitstream filter, and it seems to make the length exactly what it should be, but it also causes the output audio file to have strange regions with pure noise...

  Best regards, Jakob