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• How can I find video rotation and rotate the clip accordingly using moviepy ?

  28 mars 2022, par Tom Burrows

  I'm using moviepy to import some videos, but the videos that should be in portrait mode are imported in landscape. I need to check whether the rotation has been changed, and if it has, rotate it back.

  



  Is this functionality built into moviepy ? If not, how else can I check it ?

  


• Find better VP8 parameters for robustness in UDP streaming with libav/ffmpeg

  24 octobre 2014, par lmNt

  I’m facing some problems in my video chat application, which is using libav libraries. I am sending 1080p videos encoded in VP8 as WebM container via UDP and it works quite well. Most of the time, the decoder on either side recovers from packet losses due to the transmission.

  However at some point in time it just freezes and never recovers again. This happens on both sides eventually. I was searching for VP8 codec parameters to set for increased robustness, when sending over lossy transmission channels. And I combined some of which I found, in order to increase robustness. However, it still freezes after some time of video chat.

  Here are the parameters I am currently using.

    pVidCodecCtx->codec_id     = AV_CODEC_ID_VP8;
  
    pVidCodecCtx->codec_type   = AVMEDIA_TYPE_VIDEO;
  
    pVidCodecCtx->width        = frmQ->pCodecCtx->width; //1920
  
    pVidCodecCtx->height       = frmQ->pCodecCtx->height; //1080
  
    pVidCodecCtx->time_base    = frmQ->pCodecCtx->time_base;
  
    pVidCodecCtx->pix_fmt      = PIX_FMT_YUV420P;
  
    pVidCodecCtx->qmin         = 4;
  
    pVidCodecCtx->qmax         = 56;
  
    pVidCodecCtx->bit_rate     = pVidCodecCtx->width * pVidCodecCtx->height * 6;
  
    pVidCodecCtx->slices       = 8;
  
    pVidCodecCtx->profile      = 3;
  
    pVidCodecCtx->thread_count = 3;
  
    pVidCodecCtx->keyint_min   = 5;
  
    av_dict_set(&pDictCodecOpts, "rc_lookahead", "0", 0);
  
    av_dict_set(&pDictCodecOpts, "quality", "realtime", 0);
  
    av_dict_set(&pDictCodecOpts, "deadline", "realtime", 0);
  
    av_dict_set(&pDictCodecOpts, "max-intra-rate", "0", 0);
  
    av_dict_set(&pDictCodecOpts, "qcomp", "0", 0);
  
    av_dict_set(&pDictCodecOpts, "default", "er", 0);
  
    av_dict_set(&pDictCodecOpts, "error_resilient", "er", 0);
  
    av_dict_set(&pDictCodecOpts, "partitions", "er", 0);

  Most of the parameters I extracted from the ffmpeg code for the vpx encoder.

  Do I also have to set parameters for the decoder in order to increase error resilience ?
  Or am I missing some parameters in the encoder or setting them incorrectly. Any help or hints are greatly appreciated.

• Integrating ffmpeg in xcode5, Cannot find gcc

  22 juin 2014, par user2007547

  I have been trying to integrate ffmpeg in xcode5.
  The step [here][1]

  [1] : FFMPEG integration on iphone/ ipad project says that cc parameter needs to be gcc in iphoneOs.platform.

  But I could not find it in my xcode5.
  It is present in xcode 4.6.3 that I have.

  I tried the ./configure command with cc as gcc from xcode4.
  Something like this :

  ./configure --prefix=armv7 --disable-ffmpeg --disable-ffplay --disable-ffprobe --disable-    ffserver --enable-avresample --enable-cross-compile --   sysroot="/Applications/Xcode5.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS7.0.sdk" --target-os=darwin --cc="/Applications/Xcode4.6.3.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/usr/bin/gcc" --extra-cflags="-arch armv7 -mfpu=neon -miphoneos-version-min=6.0" --extra-ldflags="-arch armv7 -isysroot /Applications/Xcode5.app/Contents/Developer/Platforms/iPhoneOS.platform/Developer/SDKs/iPhoneOS7.0.sdk -miphoneos-version-min=6.0" --arch=arm --cpu=cortex-a9 --enable-pic

  It works ok but then the make command after fails like this :

  libavcodec/arm/mdct_vfp.S:113:unknown register alias 'TCOS_D0_HEAD'
  
  libavcodec/arm/mdct_vfp.S:114:unknown register alias 'TCOS_D1_HEAD'
  
  libavcodec/arm/mdct_vfp.S:115:unknown register alias 'TCOS_S0_TAIL'
  
  make: *** [libavcodec/arm/mdct_vfp.o] Error 1

  What am I doing wrong here ?? Where can I find gcc for xcode5 ??