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• Webcam stream with FFMpeg on iPhone

  6 décembre 2011, par Saphrosit

  I'm trying to send and show a webcam stream from a linux server to an iPhone app. I don't know if it's the best solution, but I downloaded and installed FFMpeg on the linux server (following, for those who want to know, this tutorial).
  FFMpeg is working fine. After a lots of wandering, I managed to send a stream to the client launching

  ffmpeg  -s 320x240 -f video4linux2 -i /dev/video0 -f mpegts -vcodec libx264 udp://192.168.1.34:1234

  where 192.168.1.34 is the address of the client. Actually the client is a Mac, but it is supposed to be an iPhone. I know the stream is sent and received correctly (tested in different ways).
  However I didn't managed to watch the stream directly on the iPhone.
  I thought of different (possible) solutions :

  • first solution : store incoming data in a NSMutableData object. Then, when the stream ends, store it and then play it using a MPMoviePlayerController. Here's the code :

    [video writeToFile:@"videoStream.m4v" atomically:YES];
    
    NSURL *url = [NSURL fileURLWithPath:@"videoStream.m4v"];
    
    
    
    MPMoviePlayerController *videoController = [[MPMoviePlayerController alloc] initWithContentURL:url];
    
    
    
    [videoController.view setFrame:CGRectMake(100, 100, 150, 150)];
    
    
    
    [self.view addSubview:videoController.view];
    
    
    
    [videoController play];

    the problem of this solution is that nothing is played (I only see a black square), even if the video is saved correctly (I can play it directly from my disk using VLC). Besides, it's not such a great idea. It's just to make things work.

  • Second solution : use CMSampleBufferRef to store the incoming video. Much more problems comes with this solution : first of all, there's no CoreMedia.framework in my system. Besides I do not get well what does this class represents and what should I do to make it works : I mean if I start (somehow) filling this "SampleBuffer" with bytes I receive from UDP connection, then it will automatically call the CMSampleBufferMakeDataReadyCallback function I set during creation ? If yes, when ? When the single frame is completed or when the whole stream is received ?

  • Third solution : use AVFoundation framework (neither this is actually available on my Mac). I did not understand if it's actually possible to start recording from a remote source or even from a NSMutableData, a char* or something like that. On AVFoundation Programming Guide I didn't find any reference that say if it's possible or not.

  I don't know which one of this solution is the best for my purpose. ANY suggestion would be appreciate.

  Besides, there's also another problem : I didn't use any segmenter program to send the video. Now, if I'm not getting wrong, segmenter needs to split the source video in smaller/shorter video easier to send. If it is right, then maybe it's not strictly necessary to make things work (may be added later). However, since the server is running under linux, I cannot use Apple's mediastreamsegmeter. May someone suggest an opensource segmenter to use in association with FFMpeg ?

  ---

  UPDATE : I edited my question adding more informations on what I did since now and what my doubts are.

• 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>

• FFMPEG : Videos converted from FLV to MP4 does not play in iPod but works in iPhone

  3 juin 2012, par Shakti Singh

  I used below command to convert videos from FLV,M4V to MP4.

  ffmpeg -y -i video_1336406262.flv -vcodec libx264 -vpre slow -vpre
  ipod640 -b 250k -bt 50k -acodec libfaac -ac 2 -ar 48000 -ab 64k -s
  480x320 video_1336406262.mp4

  The videos converted from M4V to MP4 are playing very well in both iPhone and iPod but the videos converted from FLV to MP4 does not work in iPod but does in iPhone.

  In the video area of HTML5 page iPod even does not show the play symbol.

  Could someone help here ?

  I am using the same command to convert from both FLV and M4V to MP4.

  Thanks