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• Revision 502912de3a : changed to comply with strict aliasing rule The clamp operation may not affect

  28 octobre 2013, par Yaowu Xu

  Changed Paths :
   Modify /vp8/decoder/decodemv.c

  
  
  changed to comply with strict aliasing rule

  The clamp operation may not affect the values of the final assigned mv
  where compiler may make use of strict aliasing rule to optimize out the
  clamp operation. This change made the code segments to better comply
  the strict aliasing rule.

  Change-Id : I24502ff18bd4f9e62507a879cc8760a91a0fd07e

• iPhone camera shooting video using the AVCaptureSession and using ffmpeg CMSampleBufferRef a change in h.264 format is the issue. please advice

  4 janvier 2012, par isaiah

  My goal is h.264/AAC , mpeg2-ts streaming to server from iphone device.

  Current my source is FFmpeg+libx264 compile success. I Know gnu License. I want the demo program.

  I'm want to know that

  1.CMSampleBufferRef to AVPicture data is success ?

   avpicture_fill((AVPicture*)pFrame, rawPixelBase, PIX_FMT_RGB32, width, height);
  
    pFrame linesize and data is not null but pst -9233123123 . outpic also .
  
   Because of this I have to guess 'non-strictly-monotonic PTS' message 

  2.This log is repeat.

  encoding frame (size= 0)
  
  encoding frame = "" , 'avcodec_encode_video' return 0 is success but always 0 . 

  I don't know what to do...

  2011-06-01 15:15:14.199 AVCam[1993:7303] pFrame = avcodec_alloc_frame(); 
  
  2011-06-01 15:15:14.207 AVCam[1993:7303] avpicture_fill = 1228800
  
  Video encoding
  
  2011-0601 15:5:14.215 AVCam[1993:7303] codec = 5841844
  
  [libx264 @ 0x1441e00] using cpu capabilities: ARMv6 NEON
  
  [libx264 @ 0x1441e00] profile Constrained Baseline, level 2.0[libx264 @ 0x1441e00] non-strictly-monotonic PTS
  
  encoding frame (size=    0)
  
  encoding frame 
  
  [libx264 @ 0x1441e00] final ratefactor: 26.74

  3.I have to guess 'non-strictly-monotonic PTS' message is the cause of all problems.
  what is this 'non-strictly-monotonic PTS' .

   this is source 

  (void)        captureOutput:(AVCaptureOutput *)captureOutput 
  
          didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer 
  
                 fromConnection:(AVCaptureConnection *)connection
  
  {
  
  
  
      if( !CMSampleBufferDataIsReady(sampleBuffer) )
  
      {
  
          NSLog( @"sample buffer is not ready. Skipping sample" );
  
          return;
  
      }
  
  
  
  
  
      if( [isRecordingNow isEqualToString:@"YES"] )
  
      {
  
          lastSampleTime = CMSampleBufferGetPresentationTimeStamp(sampleBuffer);
  
          if( videoWriter.status != AVAssetWriterStatusWriting  )
  
          {
  
              [videoWriter startWriting];
  
              [videoWriter startSessionAtSourceTime:lastSampleTime];
  
          }
  
  
  
          if( captureOutput == videooutput )
  
          {
  
              [self newVideoSample:sampleBuffer];
  
  
  
              CVImageBufferRef pixelBuffer = CMSampleBufferGetImageBuffer(sampleBuffer); 
  
              CVPixelBufferLockBaseAddress(pixelBuffer, 0); 
  
  
  
              // access the data 
  
              int width = CVPixelBufferGetWidth(pixelBuffer); 
  
              int height = CVPixelBufferGetHeight(pixelBuffer); 
  
              unsigned char *rawPixelBase = (unsigned char *)CVPixelBufferGetBaseAddress(pixelBuffer); 
  
  
  
              AVFrame *pFrame; 
  
              pFrame = avcodec_alloc_frame(); 
  
              pFrame->quality = 0;
  
  
  
              NSLog(@"pFrame = avcodec_alloc_frame(); ");
  
  
  
  //          int bytesPerRow = CVPixelBufferGetBytesPerRowOfPlane(pixelBuffer, 0);
  
  
  
  //          int bytesSize = height * bytesPerRow ;  
  
  
  
  //          unsigned char *pixel = (unsigned char*)malloc(bytesSize);
  
  
  
  //          unsigned char *rowBase = CVPixelBufferGetBaseAddressOfPlane(pixelBuffer, 0);
  
  
  
  //          memcpy (pixel, rowBase, bytesSize);
  
  
  
  
  
              int avpicture_fillNum = avpicture_fill((AVPicture*)pFrame, rawPixelBase, PIX_FMT_RGB32, width, height);//PIX_FMT_RGB32//PIX_FMT_RGB8
  
              //NSLog(@"rawPixelBase = %i , rawPixelBase -s = %s",rawPixelBase, rawPixelBase); 
  
              NSLog(@"avpicture_fill = %i",avpicture_fillNum);
  
              //NSLog(@"width = %i,height = %i",width, height);
  
  
  
  
  
  
  
              // Do something with the raw pixels here 
  
  
  
              CVPixelBufferUnlockBaseAddress(pixelBuffer, 0); 
  
  
  
              //avcodec_init();
  
              //avdevice_register_all();
  
              av_register_all();
  
  
  
  
  
  
  
  
  
  
  
              AVCodec *codec;
  
              AVCodecContext *c= NULL;
  
              int  out_size, size, outbuf_size;
  
              //FILE *f;
  
              uint8_t *outbuf;
  
  
  
              printf("Video encoding\n");
  
  
  
              /* find the mpeg video encoder */
  
              codec =avcodec_find_encoder(CODEC_ID_H264);//avcodec_find_encoder_by_name("libx264"); //avcodec_find_encoder(CODEC_ID_H264);//CODEC_ID_H264);
  
              NSLog(@"codec = %i",codec);
  
              if (!codec) {
  
                  fprintf(stderr, "codec not found\n");
  
                  exit(1);
  
              }
  
  
  
              c= avcodec_alloc_context();
  
  
  
              /* put sample parameters */
  
              c->bit_rate = 400000;
  
              c->bit_rate_tolerance = 10;
  
              c->me_method = 2;
  
              /* resolution must be a multiple of two */
  
              c->width = 352;//width;//352;
  
              c->height = 288;//height;//288;
  
              /* frames per second */
  
              c->time_base= (AVRational){1,25};
  
              c->gop_size = 10;//25; /* emit one intra frame every ten frames */
  
              //c->max_b_frames=1;
  
              c->pix_fmt = PIX_FMT_YUV420P;
  
  
  
              c ->me_range = 16;
  
              c ->max_qdiff = 4;
  
              c ->qmin = 10;
  
              c ->qmax = 51;
  
              c ->qcompress = 0.6f;
  
  
  
              /* open it */
  
              if (avcodec_open(c, codec) < 0) {
  
                  fprintf(stderr, "could not open codec\n");
  
                  exit(1);
  
              }
  
  
  
  
  
              /* alloc image and output buffer */
  
              outbuf_size = 100000;
  
              outbuf = malloc(outbuf_size);
  
              size = c->width * c->height;
  
  
  
              AVFrame* outpic = avcodec_alloc_frame();
  
              int nbytes = avpicture_get_size(PIX_FMT_YUV420P, c->width, c->height);
  
  
  
              //create buffer for the output image
  
              uint8_t* outbuffer = (uint8_t*)av_malloc(nbytes);
  
  
  
  #pragma mark -  
  
  
  
              fflush(stdout);
  
  
  
  <pre>//         int numBytes = avpicture_get_size(PIX_FMT_YUV420P, c->width, c->height);
  
  //          uint8_t *buffer = (uint8_t *)av_malloc(numBytes*sizeof(uint8_t));
  
  //          
  
  //          //UIImage *image = [UIImage imageNamed:[NSString stringWithFormat:@"10%d", i]];
  
  //          CGImageRef newCgImage = [self imageFromSampleBuffer:sampleBuffer];//[image CGImage];
  
  //          
  
  //          CGDataProviderRef dataProvider = CGImageGetDataProvider(newCgImage);
  
  //          CFDataRef bitmapData = CGDataProviderCopyData(dataProvider);
  
  //          buffer = (uint8_t *)CFDataGetBytePtr(bitmapData);   
  
  //          
  
  //          avpicture_fill((AVPicture*)pFrame, buffer, PIX_FMT_RGB8, c->width, c->height);
  
              avpicture_fill((AVPicture*)outpic, outbuffer, PIX_FMT_YUV420P, c->width, c->height);
  
  
  
              struct SwsContext* fooContext = sws_getContext(c->width, c->height, 
  
                                                             PIX_FMT_RGB8, 
  
                                                             c->width, c->height, 
  
                                                             PIX_FMT_YUV420P, 
  
                                                             SWS_FAST_BILINEAR, NULL, NULL, NULL);
  
  
  
              //perform the conversion
  
              sws_scale(fooContext, pFrame->data, pFrame->linesize, 0, c->height, outpic->data, outpic->linesize);
  
              // Here is where I try to convert to YUV
  
  
  
              /* encode the image */
  
  
  
              out_size = avcodec_encode_video(c, outbuf, outbuf_size, outpic);
  
              printf("encoding frame (size=%5d)\n", out_size);
  
              printf("encoding frame %s\n", outbuf);
  
  
  
  
  
              //fwrite(outbuf, 1, out_size, f);
  
  
  
              //              free(buffer);
  
              //              buffer = NULL;      
  
  
  
  
  
  
  
              /* add sequence end code to have a real mpeg file */
  
  //          outbuf[0] = 0x00;
  
  //          outbuf[1] = 0x00;
  
  //          outbuf[2] = 0x01;
  
  //          outbuf[3] = 0xb7;
  
              //fwrite(outbuf, 1, 4, f);
  
              //fclose(f);
  
              free(outbuf);
  
  
  
              avcodec_close(c);
  
              av_free(c);
  
              av_free(pFrame);
  
              printf("\n");
  
  </pre>

• Convert .mov to .mp4 and keep alpha channel using FFMPEG

  5 mai 2015, par Mark S.

  I am trying to convert a .mov file that is Quicktime with Alpha Channel to a .mp4 movie. I am using FFMPEG and I can successfully convert the video to a .mp4 video, but I loose the alpha channel.

  Here is the command I am running :
  ffmpeg -i BLUE_LOWER_THIRD.mov -vcodec libx264 -vpre medium blue_lower_third.mp4

  I am running this on Ubuntu 11.10. Here is the information about my install of ffmpeg.

  ffmpeg version 0.7.3-4:0.7.3-0ubuntu0.11.10.1, Copyright (c) 2000-2011 the Libav developers
  
    built on Jan  4 2012 16:08:51 with gcc 4.6.1
  
    configuration: --extra-version='4:0.7.3-0ubuntu0.11.10.1' --arch=amd64 --prefix=/usr --enable-vdpau --enable-bzlib --enable-libgsm --enable-libschroedinger --enable-libspeex --enable-libtheora --enable-libvorbis --enable-pthreads --enable-zlib --enable-libvpx --enable-runtime-cpudetect --enable-vaapi --enable-gpl --enable-postproc --enable-swscale --enable-x11grab --enable-libdc1394 --enable-shared --disable-static
  
    avutil      configuration: --extra-version='4:0.7.3ubuntu0.11.10.1' --arch=amd64 --prefix=/usr --enable-vdpau --enable-bzlib --enable-libgsm --enable-libschroedinger --enable-libspeex --enable-libtheora --enable-libvorbis --enable-pthreads --enable-zlib --enable-libvpx --enable-runtime-cpudetect --enable-vaapi --enable-libopenjpeg --enable-gpl --enable-postproc --enable-swscale --enable-x11grab --enable-libdirac --enable-libmp3lame --enable-librtmp --enable-libx264 --enable-libxvid --enable-libvo-aacenc --enable-version3 --enable-libvo-amrwbenc --enable-version3 --enable-libdc1394 --enable-shared --disable-static
  
    avcodec     configuration: --extra-version='4:0.7.3ubuntu0.11.10.1' --arch=amd64 --prefix=/usr --enable-vdpau --enable-bzlib --enable-libgsm --enable-libschroedinger --enable-libspeex --enable-libtheora --enable-libvorbis --enable-pthreads --enable-zlib --enable-libvpx --enable-runtime-cpudetect --enable-vaapi --enable-libopenjpeg --enable-gpl --enable-postproc --enable-swscale --enable-x11grab --enable-libdirac --enable-libmp3lame --enable-librtmp --enable-libx264 --enable-libxvid --enable-libvo-aacenc --enable-version3 --enable-libvo-amrwbenc --enable-version3 --enable-libdc1394 --enable-shared --disable-static
  
    avformat    configuration: --extra-version='4:0.7.3ubuntu0.11.10.1' --arch=amd64 --prefix=/usr --enable-vdpau --enable-bzlib --enable-libgsm --enable-libschroedinger --enable-libspeex --enable-libtheora --enable-libvorbis --enable-pthreads --enable-zlib --enable-libvpx --enable-runtime-cpudetect --enable-vaapi --enable-libopenjpeg --enable-gpl --enable-postproc --enable-swscale --enable-x11grab --enable-libdirac --enable-libmp3lame --enable-librtmp --enable-libx264 --enable-libxvid --enable-libvo-aacenc --enable-version3 --enable-libvo-amrwbenc --enable-version3 --enable-libdc1394 --enable-shared --disable-static
  
    libavutil    51.  7. 0 / 51.  7. 0
  
    libavcodec   53.  6. 0 / 53.  6. 0
  
    libavformat  53.  3. 0 / 53.  3. 0
  
    libavdevice  53.  0. 0 / 53.  0. 0
  
    libavfilter   2.  4. 0 /  2.  4. 0
  
    libswscale    2.  0. 0 /  2.  0. 0
  
    libpostproc  52.  0. 0 / 52.  0. 0

  Is it possible to have alpha channel in an mp4 file ? If so, how do you do it with FFMPEG ?

  Edit : This is the output from running the command.

  Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'BLUE_LOWER_THIRD.mov':
  
    Metadata:
  
      major_brand     : qt  
  
      minor_version   : 537199360
  
      compatible_brands: qt  
  
      creation_time   : 2010-12-21 10:36:51
  
    Duration: 00:00:15.00, start: 0.000000, bitrate: 8050 kb/s
  
      Stream #0.0(eng): Video: png, bgra, 1920x1080, 8043 kb/s, PAR 1920:1920 DAR 16:9, 30 fps, 30 tbr, 30 tbn, 30 tbc
  
      Metadata:
  
        creation_time   : 2010-12-21 10:36:51
  
      Stream #0.1(eng): Data: tmcd / 0x64636D74, 0 kb/s
  
      Metadata:
  
        creation_time   : 2010-12-21 10:39:48
  
  File 'blue_lower_third.mp4' already exists. Overwrite ? [y/N] y
  
  Incompatible pixel format 'bgra' for codec 'libx264', auto-selecting format 'yuv420p'
  
  [buffer @ 0x7e3d80] w:1920 h:1080 pixfmt:bgra
  
  [ffsink @ 0x7edda0] auto-inserting filter 'auto-inserted scaler 0' between the filter 'src' and the filter 'out'
  
  [scale @ 0x7fc480] w:1920 h:1080 fmt:bgra -> w:1920 h:1080 fmt:yuv420p flags:0x4
  
  [libx264 @ 0x7fcf20] using SAR=1/1
  
  [libx264 @ 0x7fcf20] using cpu capabilities: MMX2 SSE2Fast SSSE3 FastShuffle Cache64
  
  [libx264 @ 0x7fcf20] profile High, level 4.0
  
  [libx264 @ 0x7fcf20] 264 - core 116 r2042 178455c - H.264/MPEG-4 AVC codec - Copyleft 2003-2011 - http://www.videolan.org/x264.html - options: cabac=1 ref=3 deblock=1:0:0 analyse=0x3:0x113 me=hex subme=7 psy=1 psy_rd=1.00:0.00 mixed_ref=1 me_range=16 chroma_me=1 trellis=1 8x8dct=1 cqm=0 deadzone=21,11 fast_pskip=1 chroma_qp_offset=-2 threads=1 sliced_threads=0 nr=0 decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=3 b_pyramid=2 b_adapt=1 b_bias=0 direct=1 weightb=1 open_gop=0 weightp=2 keyint=250 keyint_min=25 scenecut=40 intra_refresh=0 rc_lookahead=40 rc=abr mbtree=1 bitrate=200 ratetol=1.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 ip_ratio=1.41 aq=1:1.00
  
  Output #0, mp4, to 'blue_lower_third.mp4':
  
    Metadata:
  
      major_brand     : qt  
  
      minor_version   : 537199360
  
      compatible_brands: qt  
  
      creation_time   : 2010-12-21 10:36:51
  
      encoder         : Lavf53.3.0
  
      Stream #0.0(eng): Video: libx264, yuv420p, 1920x1080 [PAR 1920:1920 DAR 16:9], q=0-69, 200 kb/s, 30 tbn, 30 tbc
  
      Metadata:
  
        creation_time   : 2010-12-21 10:36:51
  
  Stream mapping:
  
    Stream #0.0 -> #0.0
  
  Press ctrl-c to stop encoding
  
  frame=  450 fps= 11 q=9.0 Lsize=      83kB time=14.93 bitrate=  45.7kbits/s    its/s    
  
  video:75kB audio:0kB global headers:0kB muxing overhead 10.287784%
  
  frame I:2     Avg QP:18.30  size:  2584
  
  [libx264 @ 0x7fcf20] frame P:118   Avg QP:16.22  size:   310
  
  [libx264 @ 0x7fcf20] frame B:330   Avg QP:16.75  size:   106
  
  [libx264 @ 0x7fcf20] consecutive B-frames:  1.8%  0.9%  1.3% 96.0%
  
  [libx264 @ 0x7fcf20] mb I  I16..4: 49.7% 50.0%  0.3%
  
  [libx264 @ 0x7fcf20] mb P  I16..4:  0.5%  0.0%  0.0%  P16..4:  0.3%  0.0%  0.0%  0.0%      0.0%    skip:99.0%
  
  [libx264 @ 0x7fcf20] mb B  I16..4:  0.0%  0.0%  0.0%  B16..8:  0.3%  0.0%  0.0%  direct: 0.0%  skip:99.6%  L0:37.2% L1:62.6% BI: 0.2%
  
  [libx264 @ 0x7fcf20] final ratefactor: 9.32
  
  [libx264 @ 0x7fcf20] 8x8 transform intra:38.0% inter:56.1%
  
  [libx264 @ 0x7fcf20] coded y,uvDC,uvAC intra: 0.9% 4.2% 2.9% inter: 0.0% 0.1% 0.0%
  
  [libx264 @ 0x7fcf20] i16 v,h,dc,p: 64% 32%  1%  3%
  
  [libx264 @ 0x7fcf20] i8 v,h,dc,ddl,ddr,vr,hd,vl,hu:  0%  2% 97%  0%  1%  0%  0%  0%  0%
  
  [libx264 @ 0x7fcf20] i4 v,h,dc,ddl,ddr,vr,hd,vl,hu:  5% 60% 23%  2%  6%  1%  1%  1%  2%
  
  [libx264 @ 0x7fcf20] i8c dc,h,v,p: 86% 13%  1%  0%
  
  [libx264 @ 0x7fcf20] Weighted P-Frames: Y:0.0% UV:0.0%
  
  [libx264 @ 0x7fcf20] ref P L0: 79.4%  2.1% 13.2%  5.2%
  
  [libx264 @ 0x7fcf20] ref B L0: 61.1% 37.7%  1.2%
  
  [libx264 @ 0x7fcf20] ref B L1: 92.3%  7.7%
  
  [libx264 @ 0x7fcf20] kb/s:40.85