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• ffmpeg start_time is negative

  8 décembre 2016, par Alex Bollbach

  I’m using ffmpeg to segment a video by start/end times. For example, I have a set of time [1], and I’d call ffmpeg 3 times here to create the three 2 second videos at times 0, 2, and 4.

  My problem is that these times (which are correct) are not correctly segmenting the video. When I inspect the stats of the video with ffprobe -i test.mov -show_format, I noticed start_time=-0.381044. I also know that this seems to be caused by trimming a video in QuickTime to produce this video. In order to correct this, I must add (start + 0.381044) somewhere in my code, and the output is fine.

  So, why is the start_time set to a negative value by the quicktime trimming ? How can I set start_time=0, so my code can work without the + 0.381044 ?

• Revert "swscale : disable ARM code until its build failure with clang/iphone is fixed"

  12 janvier 2014, par Michael Niedermayer

  Revert "swscale : disable ARM code until its build failure with clang/iphone is fixed"
  This reverts commit c8c7736c1025bcf5bb27e104a0d0eae749408739.
  

  • [DH] libswscale/arm/Makefile
  • [DH] libswscale/swscale_unscaled.c

• Iphone Streaming and playing Audio Problem

  20 août 2011, par KayKay

  I am trying to make an app that plays audio stream using ffmpeg, libmms.
  I can open mms server, get stream, and decode audio frame to raw frame using suitable codec.
  However I don't know how to do next.
  I think I must use AudioToolbox/AudioToolbox.h and make audioqueue.
  but however when I give audioqueuebuffer decode buffer's memory and play, Only plays the white noise.
  Here is my code.

  What am i missing ?
  Any comment and hint is very appreciated.
  Thanks very much.

  while(av_read_frame(pFormatCtx, &pkt)>=0)
  
  {
  
      int pkt_decoded_len = 0;
  
      int frame_decoded_len;
  
      int decode_buff_remain=AVCODEC_MAX_AUDIO_FRAME_SIZE * 5;
  
      if(pkt.stream_index==audiostream)
  
      {
  
          frame_decoded_len=decode_buff_remain;
  
          int16_t *decode_buff_ptr = decode_buffer;
  
          int decoded_tot_len=0;
  
          pkt_decoded_len = avcodec_decode_audio2(pCodecCtx, decode_buff_ptr, &frame_decoded_len,
  
                                                  pkt.data, pkt.size);
  
          if (pkt_decoded_len <0) break;
  
          AudioQueueAllocateBuffer(audioQueue, kBufferSize, &buffers[i]);
  
          AQOutputCallback(self, audioQueue, buffers[i], pkt_decoded_len);
  
  
  
          if(i == 1){
  
              AudioQueueSetParameter(audioQueue, kAudioQueueParam_Volume, 1.0);
  
              AudioQueueStart(audioQueue, NULL);
  
          }
  
          i++;
  
      }
  
  }
  
  
  
  
  
  void AQOutputCallback(void *inData, AudioQueueRef inAQ, AudioQueueBufferRef inBuffer, int copySize)
  
  {
  
      mmsDemoViewController *staticApp = (mmsDemoViewController *)inData;
  
      [staticApp handleBufferCompleteForQueue:inAQ buffer:inBuffer size:copySize];
  
  }
  
  
  
  - (void)handleBufferCompleteForQueue:(AudioQueueRef)inAQ
  
                            buffer:(AudioQueueBufferRef)inBuffer
  
                              size:(int)copySize
  
  {
  
      inBuffer->mAudioDataByteSize = inBuffer->mAudioDataBytesCapacity;
  
      memcpy((char*)inBuffer->mAudioData, (const char*)decode_buffer, copySize);
  
  
  
      AudioQueueEnqueueBuffer(inAQ, inBuffer, 0, NULL);
  
  }