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• Revision c8ed36432e : Non-uniform quantization experiment This framework allows lower quantization bi

  4 mars 2015, par Deb Mukherjee

  Changed Paths :
   Modify /configure

  
   Modify /vp9/common/vp9_blockd.h

  
   Modify /vp9/common/vp9_onyxc_int.h

  
   Modify /vp9/common/vp9_quant_common.c

  
   Modify /vp9/common/vp9_quant_common.h

  
   Modify /vp9/common/vp9_rtcd_defs.pl

  
   Modify /vp9/decoder/vp9_decodeframe.c

  
   Modify /vp9/decoder/vp9_detokenize.c

  
   Modify /vp9/encoder/vp9_block.h

  
   Modify /vp9/encoder/vp9_encodemb.c

  
   Modify /vp9/encoder/vp9_encodemb.h

  
   Modify /vp9/encoder/vp9_quantize.c

  
   Modify /vp9/encoder/vp9_quantize.h

  
   Modify /vp9/encoder/vp9_rdopt.c

  
  
  Non-uniform quantization experiment

  This framework allows lower quantization bins to be shrunk down or
  expanded to match closer the source distribution (assuming a generalized
  gaussian-like central peaky model for the coefficients) in an
  entropy-constrained sense. Specifically, the width of the bins 0-4 are
  modified as a factor of the nominal quantization step size and from 5
  onwards all bins become the same as the nominal quantization step size.
  Further, different bin width profiles as well as reconstruction values
  can be used based on the coefficient band as well as the quantization step
  size divided into 5 ranges.

  A small gain currently on derflr of about 0.16% is observed with the
  same paraemters for all q values.
  Optimizing the parameters based on qstep value is left as a TODO for now.

  Results on derflr with all expts on is +6.08% (up from 5.88%).

  Experiments are in progress to tune the parameters for different
  coefficient bands and quantization step ranges.

  Change-Id : I88429d8cb0777021bfbb689ef69b764eafb3a1de

• How to join webcam FLVs

  18 mars 2015, par Marc-André Lafortune

  I want my website to join some webcam recordings in FLV files (like this one). This needs to be done on Linux without user input. How do I do this ? For simplicity’s sake, I’ll use the same flv as both inputs in hope of getting a flv that plays the same thing twice in a row.

  That should be easy enough, right ? There’s even a full code example in the ffmpeg FAQ.

  Well, pipes seem to be giving me problems (both on my mac running Leopard and on Ubuntu 8.04) so let’s keep it simple and use normal files. Also, if I don’t specify a rate of 15 fps, the visual part plays extremely fast. The example script thus becomes :

  ffmpeg -i input.flv -vn -f u16le -acodec pcm_s16le -ac 2 -ar 44100 \
  
    - > temp.a < /dev/null
  
  ffmpeg -i input.flv -an -f yuv4mpegpipe - > temp.v < /dev/null
  
  cat temp.v temp.v > all.v
  
  cat temp.a temp.a > all.a
  
  ffmpeg -f u16le -acodec pcm_s16le -ac 2 -ar 44100 -i all.a \
  
    -f yuv4mpegpipe -i all.v -sameq -y output.flv

  Well, using this will work for the audio, but I only get the video the first time around. This seems to be the case for any flv I throw as input.flv, including the movie teasers that come with red5.

  a) Why doesn’t the example script work as advertised, in particular why do I not get all the video I’m expecting ?

  b) Why do I have to specify a framerate while Wimpy player can play the flv at the right speed ?

  The only way I found to join two flvs was to use mencoder. Problem is, mencoder doesn’t seem to join flvs :

  mencoder input.flv input.flv -o output.flv -of lavf -oac copy \
  
  -ovc lavc -lavcopts vcodec=flv

  I get a Floating point exception...

  MEncoder 1.0rc2-4.0.1 (C) 2000-2007 MPlayer Team
  
  CPU: Intel(R) Xeon(R) CPU 5150 @ 2.66GHz (Family: 6, Model: 15, Stepping: 6)
  
  CPUflags: Type: 6 MMX: 1 MMX2: 1 3DNow: 0 3DNow2: 0 SSE: 1 SSE2: 1
  
  Compiled for x86 CPU with extensions: MMX MMX2 SSE SSE2
  
  
  
  success: format: 0 data: 0x0 - 0x45b2f
  
  libavformat file format detected.
  
  [flv @ 0x697160]Unsupported audio codec (6)
  
  [flv @ 0x697160]Could not find codec parameters (Audio: 0x0006, 22050 Hz, mono)
  
  [lavf] Video stream found, -vid 0
  
  [lavf] Audio stream found, -aid 1
  
  VIDEO: [FLV1] 240x180 0bpp 1000.000 fps 0.0 kbps ( 0.0 kbyte/s)
  
  [V] filefmt:44 fourcc:0x31564C46 size:240x180 fps:1000.00 ftime:=0.0010
  
  ** MUXER_LAVF *****************************************************************
  
  REMEMBER: MEncoder's libavformat muxing is presently broken and can generate
  
  INCORRECT files in the presence of B frames. Moreover, due to bugs MPlayer
  
  will play these INCORRECT files as if nothing were wrong!
  
  *******************************************************************************
  
  OK, exit
  
  Opening video filter: [expand osd=1]
  
  Expand: -1 x -1, -1 ; -1, osd: 1, aspect: 0.000000, round: 1
  
  ==========================================================================
  
  Opening video decoder: [ffmpeg] FFmpeg's libavcodec codec family
  
  Selected video codec: [ffflv] vfm: ffmpeg (FFmpeg Flash video)
  
  ==========================================================================
  
  audiocodec: framecopy (format=6 chans=1 rate=22050 bits=16 B/s=0 sample-0)
  
  VDec: vo config request - 240 x 180 (preferred colorspace: Planar YV12)
  
  VDec: using Planar YV12 as output csp (no 0)
  
  Movie-Aspect is undefined - no prescaling applied.
  
  videocodec: libavcodec (240x180 fourcc=31564c46 [FLV1])
  
  VIDEO CODEC ID: 22
  
  AUDIO CODEC ID: 10007, TAG: 0
  
  Writing header...
  
  [NULL @ 0x67d110]codec not compatible with flv
  
  Floating point exception

  c) Is there a way for mencoder to decode and encode flvs correctly ?

  So the only way I’ve found so far to join flvs, is to use ffmpeg to go back and forth between flv and avi, and use mencoder to join the avis :

  ffmpeg -i input.flv -vcodec rawvideo -acodec pcm_s16le -r 15 file.avi
  
  mencoder -o output.avi -oac copy -ovc copy -noskip file.avi file.avi
  
  ffmpeg -i output.avi output.flv

  d) There must be a better way to achieve this... Which one ?

  e) Because of the problem of the framerate, though, only flvs with constant framerate (like the one I recorded through facebook) will be converted correctly to avis, but this won’t work for the flvs I seem to be recording (like this one or this one). Is there a way to do this for these flvs too ?

  Any help would be very appreciated.

• Merge commit ’e0046bc9c96150fa06146ace9093f06857dd7b23’

  23 mars 2015, par Michael Niedermayer

  Merge commit ’e0046bc9c96150fa06146ace9093f06857dd7b23’
  * commit ’e0046bc9c96150fa06146ace9093f06857dd7b23’ :
  
    movenc : Write the make and model metadata keys for mov style files
  Conflicts :
  
  	libavformat/movenc.c
  Merged-by : Michael Niedermayer <michaelni@gmx.at>
  

  • [DH] libavformat/movenc.c