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• Concatenating 30fps video with audio using ffmpeg

  29 juillet 2012, par Olumide

  In essence, my question is about how to specify the framerates of an input video file and the resulting, output video file when concatenating a video and an audio file.

  I am trying to concatenate a 30fps video with a 44k audio file but the video and audio parts of the result/output are out of synch. (This does not happen, or less obvious, when the framerate of the video is 24fps, suggests to me that ffmpeg has a default framerate.) I've tried specifying the framerate of the output video as well, like so

  ffmpeg -i inFile.avi -i audio.wav -b:v 2500k -r 30 outFile.mpg

  but that doesn't seem to help.

  What am I doing wrong ?

• What, if any, guarantees are there for when `nalu_process` will be called ?

  1er août 2012, par gspr

  In particular, can a call to x264_encoder_encode return before every nalu_process callback associated to it has returned ? Someone in #x264 suggested it's settings-dependent ; I'm talking here about the "zerolatency" preset.

  If the answer to the above question is yes, then how common is it, empirically ?

• Encode video using ffmpeg from javacv on Android causes native code crash

  13 décembre 2012, par gtcompscientist

  NOTE : I have updated this since originally asking the question to reflect some of what I have learned about loading live camera images into the ffmpeg libraries.

  I am using ffmpeg from javacv compiled for Android to encode/decode video for my application. (Note that originally, I was trying to use ffmpeg-java, but it has some incompatible libraries)

  Original problem : The problem that I've run into is that I am currently getting each frame as a Bitmap (just a plain android.graphics.Bitmap) and I can't figure out how to stuff that into the encoder.

  Solution in javacv's ffmpeg : Use avpicture_fill(), the format from Android is supposedly YUV420P, though I can't verify this until my encoder issues (below) are fixed.

  avcodec.avpicture_fill((AVPicture)mFrame, picPointer, avutil.PIX_FMT_YUV420P, VIDEO_WIDTH, VIDEO_HEIGHT)

  Problem Now : The line that is supposed to actually encode the data crashes the thread. I get a big native code stack trace that I'm unable to understand. Does anybody have a suggestion ?

  Here is the code that I am using to instantiate all the ffmpeg libraries :

      avcodec.avcodec_register_all();
  
      avcodec.avcodec_init();
  
      avformat.av_register_all();
  
  
  
      mCodec = avcodec.avcodec_find_encoder(avcodec.CODEC_ID_H263);
  
      if (mCodec == null)
  
      {
  
          Logging.Log("Unable to find encoder.");
  
          return;
  
      }
  
      Logging.Log("Found encoder.");
  
  
  
      mCodecCtx = avcodec.avcodec_alloc_context();
  
      mCodecCtx.bit_rate(300000);
  
      mCodecCtx.codec(mCodec);
  
      mCodecCtx.width(VIDEO_WIDTH);
  
      mCodecCtx.height(VIDEO_HEIGHT);
  
      mCodecCtx.pix_fmt(avutil.PIX_FMT_YUV420P);
  
      mCodecCtx.codec_id(avcodec.CODEC_ID_H263);
  
      mCodecCtx.codec_type(avutil.AVMEDIA_TYPE_VIDEO);
  
      AVRational ratio = new AVRational();
  
      ratio.num(1);
  
      ratio.den(30);
  
      mCodecCtx.time_base(ratio);
  
      mCodecCtx.coder_type(1);
  
      mCodecCtx.flags(mCodecCtx.flags() | avcodec.CODEC_FLAG_LOOP_FILTER);
  
      mCodecCtx.me_cmp(avcodec.FF_LOSS_CHROMA);
  
      mCodecCtx.me_method(avcodec.ME_HEX);
  
      mCodecCtx.me_subpel_quality(6);
  
      mCodecCtx.me_range(16);
  
      mCodecCtx.gop_size(30);
  
      mCodecCtx.keyint_min(10);
  
      mCodecCtx.scenechange_threshold(40);
  
      mCodecCtx.i_quant_factor((float) 0.71);
  
      mCodecCtx.b_frame_strategy(1);
  
      mCodecCtx.qcompress((float) 0.6);
  
      mCodecCtx.qmin(10);
  
      mCodecCtx.qmax(51);
  
      mCodecCtx.max_qdiff(4);
  
      mCodecCtx.max_b_frames(1);
  
      mCodecCtx.refs(2);
  
      mCodecCtx.directpred(3);
  
      mCodecCtx.trellis(1);
  
      mCodecCtx.flags2(mCodecCtx.flags2() | avcodec.CODEC_FLAG2_BPYRAMID | avcodec.CODEC_FLAG2_WPRED | avcodec.CODEC_FLAG2_8X8DCT | avcodec.CODEC_FLAG2_FASTPSKIP);
  
  
  
      if (avcodec.avcodec_open(mCodecCtx, mCodec) == 0)
  
      {
  
          Logging.Log("Unable to open encoder.");
  
          return;
  
      }
  
      Logging.Log("Encoder opened.");
  
  
  
      mFrameSize = avcodec.avpicture_get_size(avutil.PIX_FMT_YUV420P, VIDEO_WIDTH, VIDEO_HEIGHT);
  
      Logging.Log("Frame size - '" + mFrameSize + "'.");
  
      //mPic = new AVPicture(mPicSize);
  
      mFrame = avcodec.avcodec_alloc_frame();
  
      if (mFrame == null)
  
      {
  
          Logging.Log("Unable to alloc frame.");
  
      }

  This is what I want to be able to execute next :

      BytePointer picPointer = new BytePointer(data);
  
      int bBuffSize = mFrameSize;
  
  
  
      BytePointer bBuffer = new BytePointer(bBuffSize);
  
  
  
      int picSize = 0;
  
      if ((picSize = avcodec.avpicture_fill((AVPicture)mFrame, picPointer, avutil.PIX_FMT_YUV420P, VIDEO_WIDTH, VIDEO_HEIGHT)) <= 0)
  
      {
  
          Logging.Log("Couldn't convert preview to AVPicture (" + picSize + ")");
  
          return;
  
      }
  
      Logging.Log("Converted preview to AVPicture (" + picSize + ")");
  
  
  
      VCAP_Package vPackage = new VCAP_Package();
  
  
  
      if (mCodecCtx.isNull())
  
      {
  
          Logging.Log("Codec Context is null!");
  
      }
  
  
  
      //encode the image
  
      int size = avcodec.avcodec_encode_video(mCodecCtx, bBuffer, bBuffSize, mFrame);
  
  
  
      int totalSize = 0;
  
      while (size >= 0)
  
      {
  
          totalSize += size;
  
          Logging.Log("Encoded '" + size + "' bytes.");
  
          //Get any delayed frames
  
          size = avcodec.avcodec_encode_video(mCodecCtx, bBuffer, bBuffSize, null); 
  
      }
  
      Logging.Log("Finished encoding. (" + totalSize + ")");

  But, as of now, I don't know how to put the Bitmap into the right piece or if I have that setup correctly.

  A few notes about the code :
  - VIDEO_WIDTH = 352
  - VIDEO_HEIGHT = 288
  - VIDEO_FPS = 30 ;