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• HTTP Header for Duration of a MP4 for HTML 5 video

  9 mars 2014, par Mustafa

  I am trying to stream MP4 video as it is encoded from a webserver. I believe I used the appropriate flags, but it is not working correctly. When I download the video from my stream and open it with VLC, it properly shows the duration. Since a socket is not seekable, I assume it writes the metadata to end ? My Chrome browser always shows 8 seconds duration. The first 8 seconds plays at the normal speed, but afterwards the pause button turns into play button and the video plays very fast, probably as fast as it is recieved. However the audio is played at normal speed. I tried document.getElementById('myVid').duration = 20000 but it is a readonly field.

  I wonder, is there anyway to explicitly state the duration in HTTP headers or in any other way ? I cannot find any documentation about it.

  ffmpeg -i - -vcodec libx264 -acodec libvo_aacenc -ar 44100 -ac 2 -ab 128000 -f mp4 -movflags frag_keyframe+faststart pipe:1 -fflags +genpts -re -profile baseline -level 30 -preset fast

  To close-voters, that thinks it is not programming related, I use it in my own server I coded, and I need to set the duration programatically via JavaScript or setting the HTTP header. I believe it may be related to both ffmpeg or http headers, that's why I posted it here.

  app.get("/video/*", function(req,res){
  
      res.writeHead(200, {
  
          'Content-Type': 'video/mp4',
  
      });
  
      var dir = req.url.split("/").splice(2).join("/");
  
      var buf = new Buffer(dir, 'base64');
  
      var src = buf.toString();
  
  
  
      var Transcoder = require('stream-transcoder');
  
      var stream = fs.createReadStream(src);
  
      // I added my own flags to this module, they are at below:
  
      new Transcoder(stream)
  
          .videoCodec('libx264')
  
          .audioCodec("libvo_aacenc")
  
          .sampleRate(44100)
  
          .channels(2)
  
          .audioBitrate(128 * 1000)
  
          .format('mp4')
  
          .on('finish', function() {
  
              console.log("finished");
  
          })
  
          .stream().pipe(res);
  
  });

  exec function in that stream-transcoder module,

      a.push("-fflags");
  
      a.push("+genpts");
  
      a.push("-re");
  
      a.push("-profile");
  
      a.push("baseline");
  
      a.push("-level");
  
      a.push("30");
  
      a.push("-preset");
  
      a.push("fast");
  
      a.push("-strict");
  
      a.push("experimental");
  
      a.push("-frag_duration");
  
      a.push("" + 2 * (1000 * 1000));
  
      var child = spawn('ffmpeg', a, {
  
          cwd: os.tmpdir()
  
      });

• Access violation reading location 0x000000148965F000

  14 février 2014, par user3012914

  I tried to encode BMP Images, which i get from a buffer and store it as a H264 Video. I am stuck with these errors the arrive randomly and repeatedly

  I am using Visual Studio 2012

  1) Access violation reading location 0x000000148965F000.

  2)Heap corruption

  The debug shows the error at this point

      struct SwsContext* fooContext = sws_getContext(_imgWidth,_imgHeight,PIX_FMT_RGB32,c->width,c->height,PIX_FMT_YUV420P, SWS_FAST_BILINEAR,NULL,NULL,NULL);
  
                      sws_scale(fooContext, inpic->data, inpic->linesize, 0, c->height, outpic->data, outpic->linesize);    // converting frame size and format

  I guess the read violation happens due to non - pre initialized values. But i couldnt exactly understand why. I have also attached part of the code below

  PagedImage *inImg = getUpdatedInputImage(0);
  
          ML_CHECK(inImg);
  
          ImageVector imgExt = inImg->getImageExtent();
  
          if ((imgExt.x == _imgWidth) && (imgExt.y == _imgHeight))
  
          {
  
              if (((imgExt.x % 4) == 0) && ((imgExt.y % 4) == 0))
  
              {
  
                 _numFramesFld->setIntValue(_numFramesFld->getIntValue() + 1);
  
                  MLFree(unicodeFilename);
  
                  // configure header
  
                  //BITMAPINFO bitmapInfo
  
                  // read out input image and write output image into video
  
                  // get input image as an array
  
                  void* imgData = NULL;
  
                  SubImageBox imageBox(imgExt); // get the whole image
  
                  getTile(inImg, imageBox, MLuint8Type, &imgData);
  
                  MLuint8* iData = (MLuint8*)imgData;
  
                  // since we have only images with
  
                  // a z-ext of 1, we can compute the c stride as follows
  
                  int cStride = _imgWidth * _imgHeight;
  
                  int offset  = 0;
  
                  MLuint8 r=0, g=0, b=0;
  
                  // pointer into the bitmap that is
  
                  // used to write images into an video
  
                  UCHAR* dst = (UCHAR*)_bits;
  
                  for (int y = _imgHeight-1; y >= 0; y--)
  
                  { // reversely scan the image. if y-rows of DIB are set in normal order, no compression will be available.
  
                      offset = _imgWidth * y;
  
                      for (int x = 0; x < _imgWidth; x++)
  
                      {
  
                          if (_isGreyValueImage)
  
                          {
  
                              r = iData[offset + x];
  
                              *dst++ = (UCHAR)r;
  
                              *dst++ = (UCHAR)r;
  
                              *dst++ = (UCHAR)r;
  
                          } 
  
                          else
  
                          {
  
                              b = iData[offset + x]; // windows bitmap need reverse order: bgr instead of rgb
  
                              g = iData[offset + x + cStride          ];
  
                              r = iData[offset + x + cStride + cStride];
  
                              *dst++ = (UCHAR)r;
  
                              *dst++ = (UCHAR)g;
  
                              *dst++ = (UCHAR)b;
  
                          }
  
                          // alpha channel in input image is ignored
  
                      }
  
                  }
  
                  outbuf_size = 100000 + c->width*c->height*(32>>3);      // allocate output buffer
  
                  outbuf = static_cast(malloc(outbuf_size));
  
                  fileName_ = (_outputFilenameFld->getStringValue()).c_str();
  
                  FILE* f = fopen(fileName_,"wb");                    // opening video file for writing
  
                  if(!f)
  
                  {
  
                      _messageFld->setStringValue("Cannot open file");
  
                  }
  
                  else _messageFld->setStringValue("Opened video file for writing\n");
  
  
  
                  //for(i=0;i<_numFramesFld->getIntValue();i++)
  
                  //{
  
                      fflush(stdout);
  
                      int nbytes = avpicture_get_size(PIX_FMT_YUV420P, c->width, c->height);                                // allocating outbuffer
  
                      uint8_t* outbuffer = (uint8_t*)av_malloc(nbytes*sizeof(uint8_t));
  
                      AVFrame* inpic = avcodec_alloc_frame();                                                               // mandatory frame allocation
  
                      AVFrame* outpic = avcodec_alloc_frame();
  
                      //outpic->pts = (int64_t)((float)i * (1000.0/((float)(c->time_base.den))) * 90);                        // setting frame pts
  
                      avpicture_fill((AVPicture*)inpic,(uint8_t*)dst, PIX_FMT_RGB32, c->width, c->height);                            // fill image with input screenshot
  
                      avpicture_fill((AVPicture*)outpic, outbuffer, PIX_FMT_YUV420P, c->width, c->height);                  // clear output picture for buffer copy
  
                      av_image_alloc(outpic->data, outpic->linesize, c->width, c->height, c->pix_fmt, 1); 
  
  
  
                      inpic->data[0] += inpic->linesize[0]*(c->height-1);                                                   // flipping frame
  
                      inpic->linesize[0] = -inpic->linesize[0];                                                             // flipping frame
  
  
  
                      struct SwsContext* fooContext = sws_getContext(_imgWidth,_imgHeight,PIX_FMT_RGB32,c->width,c->height,PIX_FMT_YUV420P, SWS_FAST_BILINEAR,NULL,NULL,NULL);
  
                      sws_scale(fooContext, inpic->data, inpic->linesize, 0, c->height, outpic->data, outpic->linesize);    // converting frame size and format
  
                      out_size = avcodec_encode_video(c, outbuf, outbuf_size, outpic);                                      // encoding video
  
                      _messageFld->setStringValue("Encoding frame %3d (size=%5d)\n");
  
                       fwrite(outbuf, 1, out_size, f);
  
                       delete [] dst;                                                                                         // freeing memory
  
                      av_free(outbuffer);     
  
                      av_free(inpic);
  
                      av_free(outpic);
  
                      av_free(fooContext);
  
                      DeleteObject(_hbitmap);
  
  
  
                      for(int Z = 0; Z/ encode the delayed frames
  
                          fwrite(outbuf, 1, out_size, f);
  
                      }
  
                      //outbuf[0] = 0x00;
  
                      //outbuf[1] = 0x00;                                                                                               // add sequence end code to have a real mpeg file
  
                      //outbuf[2] = 0x01;
  
                      //outbuf[3] = 0xb7;
  
                      //fwrite(outbuf, 1, 4, f);
  
                      fclose(f);
  
                      avcodec_close(c);                                                                                               // freeing memory
  
                      free(outbuf);
  
                      av_free(c);
  
                      printf("Closed codec and Freed\n");
  
                  }
  
              }

• Change ffmpeg output directory

  6 mai 2019, par Filip

  Im using ffmpeg to compress footage and i want to compess the footage of a specific day but when i overwrite the files it outputs a empty stream because it writes as it reads at the same time so i want to rename the output file. Find will give the full path which is necessary but i don’t know how to change the actual file name, rather than the path.

  Any suggestions ?

  find /home/server/recordings/compress -name '*.mp4' -print0 | xargs -0 -I{} ffmpeg -i {}  -c:v libx265 -preset fast -crf 25 -x265-params "vbv-maxrate=1500:vbv-bufsize=1000" -c:a aac {}