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• How to seek one frame forward in ffmpeg [closed]

  10 mars, par Summit

  i want to seek one frame forward when i call this function but it gets stuck on the first frame seeked and does not move forward.

  


  void seekFrameUp() {
    if (!fmt_ctx || video_stream_index == -1) return;

    AVRational frame_rate = fmt_ctx->streams[video_stream_index]->r_frame_rate;
    if (frame_rate.num == 0) return;  // Avoid division by zero

    // Compute frame duration in AV_TIME_BASE_Q
    int64_t frame_duration = av_rescale_q(1,
        av_make_q(frame_rate.den, frame_rate.num),
        AV_TIME_BASE_Q);

    int64_t next_pts = requestedTimestamp + frame_duration;

    qDebug() << "Seeking forward: " << next_pts
        << " (Current PTS: " << requestedTimestamp
        << ", Frame Duration: " << frame_duration << ")";

    requestFrameAt(next_pts);

    // Update the requested timestamp after seeking
    requestedTimestamp = next_pts;
}





void requestFrameAt(int64_t timestamp) {
     {
         std::lock_guard lock(mtx);
         decoding = true;  // Ensure the thread keeps decoding when needed
     }
     cv.notify_one();
 }


void decodeLoop() {
    while (!stopThread) {
        std::unique_lock lock(mtx);
        cv.wait(lock, [this] { return decoding || stopThread; });

        if (stopThread) break;

        // Avoid redundant seeking
        if (requestedTimestamp == lastRequestedTimestamp) {
            decoding = false;
            continue;
        }

       

        lastRequestedTimestamp.store(requestedTimestamp.load());
        int64_t target_pts = av_rescale_q(requestedTimestamp, AV_TIME_BASE_Q, fmt_ctx->streams[video_stream_index]->time_base);

        target_pts = FFMAX(target_pts, 0); // Ensure it's not negative

        if (av_seek_frame(fmt_ctx, video_stream_index, target_pts, AVSEEK_FLAG_ANY) >= 0) {
            avcodec_flush_buffers(codec_ctx);  // Clear old frames from the decoder
            qDebug() << "Seek successful to PTS:" << target_pts;
        }
        else {
            qDebug() << "Seeking failed!";
            decoding = false;
            continue;
        }

        lock.unlock();

        // Keep decoding until we receive a valid frame
        bool frameDecoded = false;
        while (av_read_frame(fmt_ctx, pkt) >= 0) {
            if (pkt->stream_index == video_stream_index) {
                if (avcodec_send_packet(codec_ctx, pkt) == 0) {
                    while (avcodec_receive_frame(codec_ctx, frame) == 0) {
                        qDebug() << "FRAME DECODED ++++++++++++ PTS:" << frame->pts;
                        if (frame->pts != AV_NOPTS_VALUE) {
                            // Rescale PTS to AV_TIME_BASE_Q
                            int64_t pts_in_correct_base = av_rescale_q(frame->pts,
                                fmt_ctx->streams[video_stream_index]->time_base,
                                AV_TIME_BASE_Q);

                            // Ensure we don’t reset to 0 incorrectly
                            if (pts_in_correct_base > 0) {
                                current_pts.store(pts_in_correct_base);
                                qDebug() << "Updated current_pts to:" << current_pts.load();
                            }
                            else {
                                qDebug() << "Warning: Decoded frame has PTS <= 0, keeping last valid PTS.";
                            }
                        }
                        else {
                            qDebug() << "Invalid frame->pts (AV_NOPTS_VALUE)";
                        }

                        QImage img = convertFrameToImage(frame);
                        emit frameDecodedSignal(img);
                
                        frameDecoded = true;
                        break;  // Exit after the first valid frame
                    }

                    if (frameDecoded) {
                        decoding = (requestedTimestamp != lastRequestedTimestamp);
                        break;
                    }
                }
            }
            av_packet_unref(pkt);
        }
    }
}


  


• Creating a file from Native c code android

  17 octobre 2013, par Azhagiri

  I am trying to demux a video in android application using FFMPEG library. Everything is working fine. But when i try to create a file from the c code to write the different streams in file fopen returns NULL. I can't proceed after that. My code is

  int ret , got_frame;
  
  av_register_all();
  
  LOGE("Registered formats");
  
  err = av_open_input_file(&pFormatCtx, "file:/mnt/sdcard/input.mp4", NULL, 0, NULL);
  
  LOGE("Called open file");
  
  if(err!=0) {
  
      LOGE("Couldn't open file");
  
      return;
  
  }
  
  LOGE("Opened file");
  
  
  
  if(av_find_stream_info(pFormatCtx)<0) {
  
      LOGE("Unable to get stream info");
  
      return;
  
  }
  
  
  
  videoStream = -1;
  
  audioStream = -1;
  
  for (i=0; inb_streams; i++) {
  
      if(pFormatCtx->streams[i]->codec->codec_type==CODEC_TYPE_VIDEO) {
  
          videoStream = i;
  
          if(audioStream != -1)
  
          break;
  
      }
  
  
  
      if(pFormatCtx->streams[i]->codec->codec_type==CODEC_TYPE_AUDIO) {
  
                  audioStream = i;
  
                  if(videoStream != -1)
  
                  break;
  
              }
  
  
  
  }
  
  if(videoStream==-1) {
  
      LOGE("Unable to find video stream");
  
      return;
  
  }
  
  if(audioStream==-1) {
  
        LOGE("Unable to find audio stream");
  
        return;
  
    }
  
  
  
  LOGI("Video stream is [%d] Audio stream [%d]", videoStream,audioStream);
  
  
  
  pCodecCtx=pFormatCtx->streams[videoStream]->codec;
  
  
  
  pCodecCtxAudio=pFormatCtx->streams[audioStream]->codec;
  
  
  
  LOGI("Video size is [%d x %d]", pCodecCtx->width, pCodecCtx->height);
  
  
  
  videoOut = fopen("file:/mnt/sdcard/videoout.mp4","wb");
  
  if (videoOut == NULL) {
  
      LOGE("Unable to open output video");
  
      return;
  
     } 

  What is the problem with my code. I enabled permissions for the application to write in external storage. Also the path i specified is also correct. Help me.

• iOS allocation grow using x264 encoding

  19 juillet 2013, par cssmhyl

  I get the video yuv data in callback and save the image data by NSData.Then I put the data into NSData,And put the array to queue(NSMutableArray). These are code :

  - (void)captureOutput:(AVCaptureOutput *)captureOutput didOutputSampleBuffer:(CMSampleBufferRef)sampleBuffer fromConnection:(AVCaptureConnection *)connection{
  
  
  
      if ([Application sharedInstance].isRecording) {
  
          if (captureOutput == self.captureManager.videOutput) {
  
  
  
              uint64_t capturedHostTime = [self GetTickCount];
  
              int allSpace = capturedHostTime - lastCapturedHostTime;
  
              NSNumber *spaces = [[NSNumber alloc] initWithInt:allSpace];
  
              NSNumber *startTime = [[NSNumber alloc] initWithUnsignedLongLong:lastCapturedHostTime];
  
              lastCapturedHostTime = capturedHostTime;
  
  
  
              CVImageBufferRef pixelBuffer = CMSampleBufferGetImageBuffer(sampleBuffer);
  
  
  
              CVPixelBufferLockBaseAddress(pixelBuffer, 0);
  
  
  
              uint8_t  *baseAddress0 = (uint8_t *)CVPixelBufferGetBaseAddressOfPlane(pixelBuffer, 0);
  
              uint8_t  *baseAddress1 = (uint8_t *)CVPixelBufferGetBaseAddressOfPlane(pixelBuffer, 1);
  
  
  
              size_t width = CVPixelBufferGetWidth(pixelBuffer);
  
              size_t height = CVPixelBufferGetHeight(pixelBuffer);
  
  
  
              NSData *baseAddress0Data = [[NSData alloc] initWithBytes:baseAddress0 length:width*height];
  
              NSData *baseAddress1Data = [[NSData alloc] initWithBytes:baseAddress1 length:width*height/2];
  
              CVPixelBufferUnlockBaseAddress(pixelBuffer, 0);
  
  
  
              NSArray *array = [[NSArray alloc] initWithObjects:baseAddress0Data,baseAddress1Data,spaces,startTime ,nil];
  
              [baseAddress0Data release];
  
              [baseAddress1Data release];
  
              [spaces release];
  
              [startTime release];
  
  
  
              @synchronized([Application sharedInstance].pearVideoQueue){
  
                  [[Application sharedInstance] enqueuePearVideo:[Application sharedInstance].pearVideoQueue withData:array];
  
                  [array release];
  
              }            
  
          }
  
      }
  
  }

  now,I run an operation and get data from the queue ,then encode them by x264.I destory de array after encoding.

  - (void)main{
  
  
  
  
  
      while ([Application sharedInstance].pearVideoQueue) {
  
          if (![Application sharedInstance].isRecording) {
  
              NSLog(@"encode operation break");
  
              break;
  
          }
  
          if (![[Application sharedInstance].pearVideoQueue isQueueEmpty]) {
  
              NSArray *pearVideoArray;
  
              @synchronized([Application sharedInstance].pearVideoQueue){
  
  
  
                 pearVideoArray = [[Application sharedInstance].pearVideoQueue dequeue];
  
                  [[Application sharedInstance] encodeToH264:pearVideoArray];
  
                  [pearVideoArray release];
  
                  pearVideoArray = nil;
  
              }
  
          } else{
  
            [NSThread sleepForTimeInterval:0.01];  
  
          }
  
      }
  
  
  
  }

  this is encoding method

  - (void)encodeX264:(NSArray *)array{
  
  
  
      int         i264Nal;
  
      x264_picture_t pic_out;
  
      x264_nal_t  *p264Nal;
  
  
  
  
  
      NSNumber *st = [array lastObject];
  
      NSNumber *sp = [array objectAtIndex:2];
  
      uint64_t startTime = [st unsignedLongLongValue];
  
      int spaces = [sp intValue];
  
  
  
      NSData *baseAddress0Data = [array objectAtIndex:0];
  
      NSData *baseAddress1Data = [array objectAtIndex:1];
  
  
  
      const char *baseAddress0 = baseAddress0Data.bytes;
  
      const char *baseAddress1 = baseAddress1Data.bytes;
  
  
  
  
  
      if (baseAddress0 == nil) {
  
          return;
  
      }
  
  
  
      memcpy(p264Pic->img.plane[0], baseAddress0, PRESENT_FRAME_WIDTH*PRESENT_FRAME_HEIGHT);
  
  
  
      uint8_t * pDst1 = p264Pic->img.plane[1];
  
      uint8_t * pDst2 = p264Pic->img.plane[2];
  
      for( int i = 0; i < PRESENT_FRAME_WIDTH*PRESENT_FRAME_HEIGHT/4; i ++ )
  
      {
  
          *pDst1++ = *baseAddress1++;
  
          *pDst2++ = *baseAddress1++;
  
      }
  
  
  
      if( x264_encoder_encode( p264Handle, &p264Nal, &i264Nal, p264Pic ,&pic_out) < 0 )
  
      {
  
          fprintf( stderr, "x264_encoder_encode failed/n" );
  
      }
  
  
  
      i264Nal = 0;
  
      if (i264Nal > 0) {
  
  
  
          int i_size;
  
          int spslen =0;
  
          unsigned char spsData[1024];        
  
          char * data = (char *)szBuffer+100;
  
          memset(szBuffer, 0, sizeof(szBuffer));
  
          if (ifFirstSps) {
  
              ifFirstSps = NO;
  
              if (![Application sharedInstance].ifAudioStarted) {
  
                  NSLog(@"video first");
  
                  [Application sharedInstance].startTick = startTime;
  
                  NSLog(@"startTick: %llu",startTime);
  
                  [Application sharedInstance].ifVideoStarted = YES;
  
              }
  
          }        
  
          for (int i=0 ; inal_buffer_size < p264Nal[i].i_payload*3/2+4) {
  
                  p264Handle->nal_buffer_size = p264Nal[i].i_payload*2+4;
  
                  x264_free( p264Handle->nal_buffer );
  
                  p264Handle->nal_buffer = x264_malloc( p264Handle->nal_buffer_size );
  
              }
  
  
  
              i_size = p264Nal[i].i_payload;
  
              memcpy(data, p264Nal[i].p_payload, p264Nal[i].i_payload);
  
              int splitNum = 0;
  
              for (int i=0; i=1) {
  
                  timeSpace = spaces/(i264Nal-1)*i;
  
              }else{
  
                  timeSpace  = spaces/i264Nal*i;
  
              }            
  
              int timeStamp  = startTime-[Application sharedInstance].startTick + timeSpace;
  
  
  
              switch (type) {
  
                  case NALU_TYPE_SPS:
  
                      spslen = i_size-splitNum;
  
                      memcpy(spsData, data, spslen);                    
  
                      break;
  
                  case NALU_TYPE_PPS:
  
                      timeStamp  = timeStamp - timeSpace;
  
                      [self pushSpsAndPpsQueue:(char *)spsData andppsData:(char *)data withPPSlength:spslen andPPSlength:(i_size-splitNum) andTimeStamp:timeStamp];
  
                      break;
  
                  case NALU_TYPE_IDR:
  
                      [self pushVideoNALU:(char *)data withLength:(i_size-splitNum) ifIDR:YES andTimeStamp:timeStamp];
  
                      break;
  
                  case NALU_TYPE_SLICE:
  
                  case NALU_TYPE_SEI:
  
                      [self pushVideoNALU:(char *)data withLength:(i_size-splitNum) ifIDR:NO andTimeStamp:timeStamp];
  
                      break;
  
                  default:
  
                      break;
  
              }
  
          }
  
      }
  
  }

  the question is :
  I used instruments and found that the data I captured increase ，but NSLog
  show that the space-time I create de array and release it did not increase,and when I release ,the array's retain count is 1. the object's retain count it contains is also one.
  then I didn't encode,the memory didn't increase...I was confused...please help..
  the image pixel is 640x480.

  intruments leaks picture：