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• Flush delayed frames every a few input frames in x264

  4 avril 2014, par xpxp

  Hi I am new to x264 and know some basics. The encoding API routine used in x264 cli (x264.c) is summarized as:

  1. call x264_encoder_open and set up parameters.
  2. fetch a frame from input video and encode it with x264_encoder_encode.
  3. iterate 2. until input EOF or the given frame limit is reached.
  4. flush delayed frames.

  My problem is: other than flush x264 encoder only once at the end of encoding process, is it possible or not to flush the delayed frames within step 2? For example, I want to flush the encoder manually every 20 frames (or a GOP frames) fed into x264_encoder_encode and resume the normal process when all delayed frames are encoded. Thus as a result the video will have several flush procedures.

  Regards

• Error compiling x264 on Mac OS X

  28 mars 2014, par progdo

  I'm trying to compile and install the x264 H.264/AVC encoder. I've got gcc installed. But I get the 'No working C compiler found' error when I run:

  ./configure --enable-shared --enable-static
  

  What can I do?

  The config log said:

  /bin/gcc conftest.c  -Wall -I. -I$(SRCPATH) -falign-loops=16 -mdynamic-no-pic -o conftest
  clang: error: unknown argument: '-falign-loops=16' [-Wunused-command-line-argument-hard-error-in-future]
  clang: note: this will be a hard error (cannot be downgraded to a warning) in the future
  

• Trouble with x264 compilation on Mac OS X

  27 mars 2014, par user3454318

  I've gcc installed. But when ./configure --enable-shared --enable-static

  it gives No working C compiler found. Please help.

• x264 encoding with libav

  25 mars 2014, par user3453729

  I try to encode raw image data to x264 with libav:

  AVPacket vpkt = { 0 };
  av_init_packet(&vpkt);
  
  int got;
  int ret = avcodec_encode_video2(vcodec, &vpkt, frameyuv.get(), &got);
  
  if (!ret && got && vpkt.size) {
      if (vpkt.pts != AV_NOPTS_VALUE) {
          vpkt.pts = av_rescale_q(vpkt.pts, vcodec->time_base, videost->time_base);
      }
      if (vpkt.dts != AV_NOPTS_VALUE) {
          vpkt.dts = av_rescale_q(vpkt.dts, vcodec->time_base, videost->time_base);
      }
  
      vpkt.stream_index = videost->index;
  
      if(vcodec->coded_frame->key_frame) {
          vpkt.flags |= AV_PKT_FLAG_KEY;
      }
      /* -> will return -22 if max_b_frames > 0 */
      ret = av_interleaved_write_frame(oc, &vpkt);
  }
  

  Runs fine when vcodec->max_b_frames is set to 0, but on any other value av_interleaved_write_frame returns -22 (invalid argument).

  /* will fail */
  c->max_b_frames = 3;
  /* -> ok*/
  c->max_b_frames = 0;
  

  Why? Am i missing something?

  Codec options are

  AVDictionary *opts = NULL;
  av_dict_set(&opts, "vprofile", "baseline", 0);
  
  /* ... */
  c->codec_type = AVMEDIA_TYPE_VIDEO;
  c->bit_rate = 500 * 1000;
  c->width = VideoWidth;
  c->height = VideoHeight;
  c->time_base.den = fps;
  c->time_base.num = 1;
  c->pix_fmt = AV_PIX_FMT_YUV420P;
  

  Container format is mp4.

• x264 : Using NAL size limitation ruines the stream

  25 mars 2014, par dtumaykin

  I'm using x264 to compress a video stream from a webcam with this settings:

  x264_param_default_preset(&param, "veryfast", "zerolatency");
  
  param.i_threads = 1;
  param.i_fps_den = 1;
  param.b_annexb = 1;
  
  param.i_keyint_max = 30;
  param.rc.i_rc_method = X264_RC_CRF;
  param.rc.f_rf_constant = 25;
  param.rc.f_rf_constant_max = 35;
  
  param.b_repeat_headers = 1;
  x264_param_apply_profile(&param, "baseline");
  
  param.i_slice_max_size = X264_NAL_MAX_SIZE;
  

  I would like to fit NAL into MTU size, but if I set a small max size, the stream is ruined - it blinks randomly between black and white, with some clues of original image in background. The bigger is the max_size, less probable is for the stream to be ruined. So my question is - can we have small NALUs and a correct video stream?

  UPD: I use FFmpeg as a decoder.