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• How to read .mp4 files in opencv

  9 mai 2016, par Noah

  I am totally newbie in OpenCV, C++. Trying to read an mp4 video but found OpenCV does not support mp4, it only reads avi(I am not sure whether I am write or wrong). After an online research came to know ffmpeg is the best option to convert mp4 to avi for further processing.

  I am using OpenCV 3.0 with visual studio 2012. I saw there is a dll file, opencv_ffmpeg300.dll in OpenCV C:\opencv\build\x86\vc11\bin folder. Is there any way I can use this dll file to read and convert my video ?

  It will be really appreciating if someone can provide me some guidelines, I am lost in the OpenCV world totally.

  For video,

  Video I/O:
  
     Video for Windows:           YES
  
     DC1394 1.x:                  NO
  
     DC1394 2.x:                  NO
  
     FFMPEG:                      YES (prebuilt binaries)
  
       codec:                     YES (ver 55.18.102)
  
       format:                    YES (ver 55.12.100)
  
       util:                      YES (ver 52.38.100)
  
       swscale:                   YES (ver 2.3.100)
  
       resample:                  NO
  
       gentoo-style:              YES
  
     OpenNI:                      NO
  
     OpenNI PrimeSensor Modules:  NO
  
     OpenNI2:                     NO
  
     PvAPI:                       NO
  
     GigEVisionSDK:               NO
  
     DirectShow:                  YES
  
     Media Foundation:            NO
  
     XIMEA:                       NO
  
     Intel PerC:                  NO

• avcodec/mpegaudiodec_template : Check CRCs for layer1 and layer2

  3 août 2020, par Michael Niedermayer

  avcodec/mpegaudiodec_template : Check CRCs for layer1 and layer2
  This differs from the MPEG specification as the actual real world
  
  files do compute their CRC over variable areas and not the fixed
  
  ones listed in the specification. This is also the reason for
  
  the complexity of this code and the need to perform the CRC
  
  check for layer2 in the middle of layer2 decoding.
  Reviewed-by : Lynne <dev@lynne.ee>
  
  Signed-off-by : Michael Niedermayer <michael@niedermayer.cc>
  

  • [DH] libavcodec/mpegaudiodec_template.c

• avcodec/vdpau : Support for VDPAU accelerated HEVC decoding

  13 juin 2015, par Philip Langdale

  avcodec/vdpau : Support for VDPAU accelerated HEVC decoding
  This change introduces basic support for HEVC decoding through vdpau.
  
  Right now, there are problems with the nvidia driver/library implementation
  
  that mean that frames are incorrectly laid out in memory when they are
  
  returned from the decoder, and it is normally impossible to recover the
  
  complete decoded frame due to loss of data from alignment inconsistencies.
  I obviously hope that nvidia will be fixing it in due course - I’ve verified
  
  the problems exist with their example application.
  As such, this support is not useful for any real world application, but I
  
  believe that it is correct (with the caveat that the mangled frames may hide
  
  problems) and will work properly once the nvidia problem is fixed.
  Right now it appears that any file encoded by x265 or nvenc is decoded
  
  correctly, but that’s because these files don’t use a bunch of HEVC
  
  features.
  Quick summary :
  Features that seem to work :
  1) Short Term References
  
  2) Scaling Lists
  
  3) Tiling
  Features with known problems :
  1) Long Term References
  It’s hard to tell what’s going on here. After I read the nvidia example
  
  app that does not set the IsLongTerm flag on LTRs, and changed my code,
  
  a bunch of frames using LTR started to display correctly, but there
  
  are still samples with glitches that are related to LTRs.
  In terms of real world files, both x265 and nvenc only use short term
  
  refs from this list. The divx encoder seems similar.
  Signed-off-by : Philip Langdale <philipl@overt.org>
  

  • [DH] configure
  • [DH] libavcodec/Makefile
  • [DH] libavcodec/allcodecs.c
  • [DH] libavcodec/hevc.c
  • [DH] libavcodec/vdpau_hevc.c
  • [DH] libavcodec/vdpau_internal.h