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• How to convert a seems like NV21 rtsp stream to normal YUV420 rtmp stream ?

  22 décembre 2018, par N.Monster

  I tried to push a live stream from H264 Encode Box(Based on Hi3516)
  to Bilibili using ffmpeg command line tool, but got a totally green picture.(It is all right when I push it to my local rtmp server.)

  After searching, i got that the problem may lies in the U and V in YUV420, or NV12 and NV21.The remote server identifies error.

  I previously use
  -vcodec copy
  After change to
  -vcodec h264
  Everything go well. But cost CPU to much. Emm Re-encoder ? I don’t need this.

  So how can I convert only pixel format locally before push steam , or just tell the server my pixel format as to get a color correct picture ?

• CMSampleBuffer from Replay Kit after encoding to Mpeg-TS Video is normal, Audio is corrupted

  18 avril 2019, par Sos A

  I am trying to stream AAC encoded audio data received as CMSampleBuffer. AudioConverterFillComplexBuffer returns 0 status code.
  But after passing this data to my FFMPEG HLSWriter audio is not correctly saved (short truncated signals).
  Below is the sample code.

  static OSStatus inInputDataProc(AudioConverterRef inAudioConverter,
  
                                      UInt32 *ioNumberDataPackets,
  
                                      AudioBufferList *ioData,
  
                                      AudioStreamPacketDescription **outDataPacketDescription,
  
                                      void *inUserData)
  
      {
  
          KFAACEncoder *encoder = (__bridge KFAACEncoder *)(inUserData);
  
          UInt32 requestedPackets = *ioNumberDataPackets;
  
  
  
          if(requestedPackets > encoder.cycledBuffer.size / 2)
  
          {
  
              //NSLog(@"PCM buffer isn't full enough!");
  
              *ioNumberDataPackets = 0;
  
              return  -1;
  
          }
  
  
  
          static size_t staticBuffSize = 4096;
  
          static void* staticBuff = nil;
  
  
  
          if(!staticBuff)
  
          {
  
              staticBuff = malloc(staticBuffSize);
  
          }
  
  
  
          size_t outputBytesSize = requestedPackets * 2;
  
          [encoder.cycledBuffer popToBuffer:staticBuff bytes: outputBytesSize];
  
          ioData->mBuffers[0].mData = staticBuff;
  
          ioData->mBuffers[0].mDataByteSize = (int)outputBytesSize;
  
  
  
          *ioNumberDataPackets = ioData->mBuffers[0].mDataByteSize / 2;
  
  
  
          return noErr;
  
      }
  
  
  
      - (void) encodeSampleBuffer:(CMSampleBufferRef)sampleBuffer
  
          {
  
              CFRetain(sampleBuffer);
  
              dispatch_async(self.encoderQueue,
  
                             ^{
  
  
  
                                 if (!_audioConverter)
  
                                 {
  
                                     [self setupAACEncoderFromSampleBuffer:sampleBuffer];
  
                                 }
  
  
  
                                 CMBlockBufferRef blockBuffer = CMSampleBufferGetDataBuffer(sampleBuffer);
  
                                 CMTime pts = CMSampleBufferGetPresentationTimeStamp(sampleBuffer);
  
                                 CFRetain(blockBuffer);
  
  
  
                                 size_t pcmBufferSize = 0;
  
                                 void* pcmBuffer = nil;
  
                                 OSStatus status = CMBlockBufferGetDataPointer(blockBuffer, 0, NULL, &pcmBufferSize, &pcmBuffer);
  
  
  
                                 [_cycledBuffer push:pcmBuffer size:pcmBufferSize];
  
  
  
                                 NSError *error = nil;
  
  
  
                                 if (status != kCMBlockBufferNoErr)
  
                                 {
  
                                     error = [NSError errorWithDomain:NSOSStatusErrorDomain code:status userInfo:nil];
  
                                 }
  
  
  
                                 memset(_aacBuffer, 0, _aacBufferSize);
  
                                 AudioBufferList outAudioBufferList = {0};
  
                                 outAudioBufferList.mNumberBuffers = 1;
  
                                 outAudioBufferList.mBuffers[0].mNumberChannels = 1;
  
                                 outAudioBufferList.mBuffers[0].mDataByteSize = _aacBufferSize;
  
                                 outAudioBufferList.mBuffers[0].mData = _aacBuffer;
  
      AudioStreamPacketDescription *outPacketDescription = NULL;
  
                                 UInt32 ioOutputDataPacketSize = 1;
  
                                 status = AudioConverterFillComplexBuffer(_audioConverter,
  
                                                                          inInputDataProc,
  
                                                                          (__bridge void *)(self),
  
                                                                          &ioOutputDataPacketSize,
  
                                                                          &outAudioBufferList,
  
                                                                          NULL);
  
  
  
  
  
  
  
       NSData *data = nil;
  
                             if (status == 0)
  
                             {
  
                                 NSData *rawAAC = [NSData dataWithBytes:outAudioBufferList.mBuffers[0].mData length:outAudioBufferList.mBuffers[0].mDataByteSize];
  
                                 if (_addADTSHeader) {
  
                                     NSData *adtsHeader = [self adtsDataForPacketLength:rawAAC.length];
  
                                     NSMutableData *fullData = [NSMutableData dataWithData:adtsHeader];
  
                                     [fullData appendData:rawAAC];
  
                                     data = fullData;
  
                                 } else {
  
                                     data = rawAAC;
  
                                 }
  
                             } else {
  
                                 error = [NSError errorWithDomain:NSOSStatusErrorDomain code:status userInfo:nil];
  
                             }
  
                             if (self.delegate) {
  
                                 KFFrame *frame = [[KFFrame alloc] initWithData:data pts:pts];
  
                                 NSLog(@"Bytes of data %lu", (unsigned long)data.length);
  
                                 dispatch_async(self.callbackQueue, ^{
  
                                     [self.delegate encoder:self encodedFrame:frame];
  
                                 });
  
                             }
  
                             CFRelease(sampleBuffer);
  
                             CFRelease(blockBuffer);
  
                         });
  
          }

• Concat video output does not skip ahead or go backwards like normal video

  6 août 2020, par JOHN DADS

  i ran this basic concat code to combine an image and audio to output an mp4 video but the output video plays perfectly except for the fact that if I want to skip ahead in the video it goes back to the original position. This was run on python

  


  audio = ffmpeg.input("beat.mp3")

picture = ffmpeg.input("image.jpg")

ffmpeg.concat(picture, audio, v=1, a=1).output("video3.mp4").run()