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• Evolution #2923 (Fermé) : Remplacement d’un document et date du document

  12 mai 2013, par cedric -

  si c’est la date du document que tu veux afficher (et pas sa date de publication) il faut simplement afficher
  [(#VAL{Y-m-d H:i:s}|date{#FICHIER|filemtime}|affdate)]
  Ça n’a pas vraiment de sens de stocker en base une date identique à celle du fichier sur le disque.

  Alternativement, la solution par plugin me semble le mieux, car cela correspond ici à un usage non générique de la date.

• armv6 : Accelerate ff_fft_calc for general case (nbits != 4)

  16 juillet 2014, par Ben Avison

  armv6 : Accelerate ff_fft_calc for general case (nbits != 4)
  The previous implementation targeted DTS Coherent Acoustics, which only
  
  requires nbits == 4 (fft16()). This case was (and still is) linked directly
  
  rather than being indirected through ff_fft_calc_vfp(), but now the full
  
  range from radix-4 up to radix-65536 is available. This benefits other codecs
  
  such as AAC and AC3.
  The implementaion is based upon the C version, with each routine larger than
  
  radix-16 calling a hierarchy of smaller FFT functions, then performing a
  
  post-processing pass. This pass benefits a lot from loop unrolling to
  
  counter the long pipelines in the VFP. A relaxed calling standard also
  
  reduces the overhead of the call hierarchy, and avoiding the excessive
  
  inlining performed by GCC probably helps with I-cache utilisation too.
  I benchmarked the result by measuring the number of gperftools samples that
  
  hit anywhere in the AAC decoder (starting from aac_decode_frame()) or
  
  specifically in the FFT routines (fft4() to fft512() and pass()) for the
  
  same sample AAC stream :
                Before          After
  
                Mean   StdDev   Mean   StdDev  Confidence  Change
  
  Audio decode  2245.5 53.1     1599.6 43.8    100.0%      +40.4%
  
  FFT routines  940.6  22.0     348.1  20.8    100.0%      +170.2%
  Signed-off-by : Martin Storsjö <martin@martin.st>
  

  • [DH] libavcodec/arm/fft_init_arm.c
  • [DH] libavcodec/arm/fft_vfp.S

• How can I split a series of clips from a video and then stitch them together without audio or video gaps ?

  16 avril 2020, par Dr. Cyber Sec

  I'm developing an application where I take a video and (1) split it up into a bunch of 1 second chunks. Then, I need to (2) stitch a subset of those chunks back together, resulting in a slice of the original video.

  



  For example, let's say I have an original, 10s clip. I split it up into 1s chunks for each second (a clip from 0s to 1s, a clip from 1s to 2s, etc.). I now need to stitch, say, seconds 2-4 together into one video.

  



  I'm currently attempting both steps using ffmpeg.

  



  For clip-cutting :

  



  ffmpeg -ss 33 -i video.ts -t 1 33to34.ts


  



  This should seek to second 33 and output a 1s clip duration, yielding a video clip containing seconds 33-34 of the original video. I noticed that ffmpeg doesn't always seek accurately, so after following the instructions in this post, which says to manually add keyframes to the parts of the video you want to cut, I tried this :

  



  First, setting the keyframes :

  



  ffmpeg -i video.ts -force_key_frames 00:00:01.000,00:00:02.000,00:00:03.000,00:00:04.000 out.ts


  



  And then cutting the clips as I did before with the new output clip.

  



  While this did get the videos to be exactly 1s long each, (which I wanted) there is a small gap (just a slight jitter) in audio when I combine the clips back together. I cannot have this, and am looking for a solution.

  



  Can anyone help me understand why this is happening and help me find a solution ? Thank you so much in advance.