Newest 'x264' Questions - Stack Overflow

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• flv file (with 264 video stream) cannot be decoded.

  5 septembre 2012, par Hong

  I have generate an flv file using libx264. It only contains video tags and some meta data. It can be played by ffmpeg, however, most commercial players cannot decode it.

  The file is at, http://www.kuaipan.cn/file/id_3690055512098762.htm, the livestream_test.flv.

  Very thanks if you know any possible errors in the file, I'm really confused now.

• x264 rate control

  31 août 2012, par Craig

  We are using the x264 encoder in a video conferencing project, we have the basic streaming video working, however, we are having trouble understanding how the various rate control settings determine the final bitrate. We set the following params:

  x264_param_t params;
  x264_param_default_preset(&params, "ultrafast", "zerolatency");
  params.i_threads = 1;
  params.i_width = width;
  params.i_height = height;
  params.i_fps_num = fps;
  params.i_keyint_max = fps;
  params.b_intra_refresh = 1;
  params.b_repeat_headers = 1;
  params.b_annexb = 1;
  
  //Set rate control stuff here
  
  x264_param_apply_profile(&params, "baseline");
  

  If we only set the params.rc.i_bitrate param, the encoder seems to massively overshoot the bitrate. If we set the i_vbv_max_bitrate & i_vbv_buffer_size params we see a bitrate which peaks (and sometimes overshoots) the i_vbv_max_bitrate setting. Obviously having tight control over the biterate is important for video conferencing, but the documentation is kind of opaque. Is anybody else using x264 for video conferencing? How are you setting the encoder? Any help appreciated, thanks in advance.

• Compiling ffmpeg : how to force it to link to a specific libx264 ?

  29 août 2012, par PaulJ

  I'm trying to compile the newest version of ffmpeg (in CentOS 5.3). I first downloaded the latest version of libx264, compiled it with --enable-static and installed it in /usr/local/. However, when I then compile ffmpeg I get this error message:

  libavcodec/libavcodec.a(libx264.o): In function `X264_init':
  /usr/local/src/ffmpeg/libavcodec/libx264.c:494: undefined reference to `x264_encoder_open_125'
  collect2: ld returned 1 exit status
  make: *** [ffmpeg_g] Error 1
  

  Searching on the net, I see that this can happen if ffmpeg is picking up an older version of libx264, which I indeed have (in /usr/lib) and can't uninstall because other pieces of software depend on it. The question is then: how can I force ffmpeg to link against the libx264 that I want? The last time I had to do this (admittedly a year ago) I also had 2 versions of libx264, and I don't remember having to do anything special. Is there a configure switch that I'm forgetting?

• libx264 2 pass encoding with mbtree option, first pass fails

  25 août 2012, par lightdee

  I'm working on an application which uses libx264. When doing 2-pass encodes, if the mbtree option is enabled, the 1st pass doesn't seem to put anything into the stats files:

      x264_1345845358591.L.mbtree.temp (size of 0)
      x264_1345845358591.L.temp
  
      $ cat x264_1345845358591.L.temp 
      #options: 288x162 fps=2997/100 timebase=100/2997 bitdepth=8 cabac=0 ref=3 
      deblock=1:0:0 analyse=0x1:0x111 me=hex subme=7 psy=1 psy_rd=1.00:0.00 
      mixed_ref=1 me_range=16 chroma_me=1 trellis=1 8x8dct=0 cqm=0 deadzone=21,11 
      fast_pskip=1 chroma_qp_offset=-2 threads=48 sliced_threads=0 nr=0 
      decimate=1 interlaced=0 bluray_compat=0 constrained_intra=0 bframes=0 
      weightp=0 keyint=250 keyint_min=25 scenecut=40 intra_refresh=0 rc_lookahead=40 
      rc=abr mbtree=1 bitrate=210 ratetol=1.0 qcomp=0.60 qpmin=0 qpmax=69 qpstep=4 
      ip_ratio=1.40 aq=1:1.00**
  

  When I do x264_encoder_open() for the 2nd pass, I get the failure message:

      x264 [error]: ratecontrol_init: can't open stats file
      x264 [error]: x264_encoder_open failed
  

  So it seems to be failing in the first pass. 2pass works fine if I turn off mbtree. I can run it with presets or tune parameters as long as mbtree is turned off. What parameter (see above list) might make mbtree fail in the first pass?

• Get output data from x264vfw filter

  23 août 2012, par no.Oby

  I need get H264 stream from x264 encoder and make some kind of live streaming server. Client will connect to the server, then via rtsp recieve video. How can I get data from x264vfw output pin? In what way better do that?