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• dxva2_hevc : properly signal the num_delta_pocs from the SPS RPS

  12 février 2016, par Hendrik Leppkes

  dxva2_hevc : properly signal the num_delta_pocs from the SPS RPS
  ucNumDeltaPocsOfRefRpsIdx needs to contain the flat value from the SPS RPS,
  
  and not the final computed value from the slice header RPS, as this calculation
  
  is done internally by the driver again.
  Sample-Id : http://trailers.divx.com/hevc/Sintel_4k_27qp_24fps_1aud_9subs.mkvi
  
  Signed-off-by : Rémi Denis-Courmont <remi@remlab.net>
  

  • [DBH] libavcodec/dxva2_hevc.c
  • [DBH] libavcodec/hevc.h
  • [DBH] libavcodec/hevc_ps.c

• lavd/v4l2 : produce a 0 byte packet when a dequeued buffer's size is unexpected

  5 juin 2019, par Stephan Hilb

  lavd/v4l2 : produce a 0 byte packet when a dequeued buffer's size is unexpected
  Behave like we do for V4L2_BUF_FLAG_ERROR, implemented in commit 28f20d2ff4 .
  For some devices (probably also related to the V4L driver implementation)
  
  it happens that when invoking the ioctl DQBUF, the returned buffer is not
  
  of the expected size. Here are two examples for such occurrences :
      [video4linux2,v4l2 @ 0x258b440] Dequeued v4l2 buffer contains 609596 bytes, but 614400 were expected. Flags : 0x00000001.
  
      /dev/video1 : Invalid data found when processing input
      [video4linux2,v4l2 @ 0x225f440] Dequeued v4l2 buffer contains 609508 bytes, but 614400 were expected. Flags : 0x00000001.
  
      /dev/video1 : Invalid data found when processing input
  For the ffmpeg CLI tool this means it will stop capturing and exit.
  The described behaviour was observed at least with one OmniVision USB
  
  web cam and with some stk1160 devices.
  If you search the web for the error message, you will find quite a few
  
  instances of this problem. Some of them experienced on other devices.
  Probably fixes ticket #4795
  Signed-off-by : Alexander Strasser <eclipse7@gmx.net>
  

  • [DH] libavdevice/v4l2.c

• aaccoder : add a new perceptual noise substitution implementation

  2 juillet 2015, par Rostislav Pehlivanov

  aaccoder : add a new perceptual noise substitution implementation
  This commit finalizes the PNS implementation previously added to the encoder
  
  by moving it to a seperate function search_for_pns() and thus making it
  
  coder-generic. This new implementation makes use of the spread field of
  
  the psy bands and the lambda quality feedback paremeter. The spread of the
  
  spectrum in a band prevents PNS from being used excessively and thus preserve
  
  more phase information in high frequencies.  The lambda parameter allows
  
  the number of PNS-marked bands to vary based on the lambda parameter and the
  
  amount of bits available, making better choices on which bands are to be marked
  
  as noise. Comparisons with the previous PNS implementation can be found
  
  here : https://trac.ffmpeg.org/attachment/wiki/Encode/AAC/
  This is V2 of the patch, the changes from the previous version being that this
  
  version uses the new band->spread metric from aacpsy and normalizes the
  
  energy using the group size. These changes were suggested by Claudio Freire
  
  on the mailing list. Another change is the use of lambda to alter the
  
  frequency threshold. This change makes the actual threshold frequencies
  
  vary between +-2Khz of what’s specified, depending on frame encoding performance.
  Reviewed-by : Claudio Freire <klaussfreire@gmail.com>
  
  Signed-off-by : Michael Niedermayer <michaelni@gmx.at>
  

  • [DH] libavcodec/aaccoder.c
  • [DH] libavcodec/aacenc.c
  • [DH] libavcodec/aacenc.h