How to set x264 baseline profile with libav in C++

Question

I am writing a small tool, which converts a video into a raw h264 file. These files shall be played later by a SIP phone. I have the following code:

  eccx->pix_fmt = PIX_FMT_YUV420P;
  eccx->width = VIDEO_FRAME_WIDTH;
  eccx->height = VIDEO_FRAME_HEIGHT;
  eccx->time_base.num = 1;
  eccx->time_base.den = VIDEO_FRAMES_PER_SEC;
  eccx->max_b_frames = 0;

  eccx->rtp_payload_size = VIDEO_RTP_PAYLOAD_SIZE;

  eccx->bit_rate = VIDEO_BIT_RATE;
  eccx->rc_max_rate = VIDEO_BIT_RATE;
  eccx->rc_buffer_size = VIDEO_BIT_RATE * 2;

  eccx->flags |= CODEC_FLAG_QP_RD;
  eccx->flags |= CODEC_FLAG_LOW_DELAY;
  eccx->flags |= CODEC_FLAG_QSCALE;
  eccx->flags |= CODEC_FLAG_EMU_EDGE;

  eccx->mb_decision = FF_MB_DECISION_SIMPLE;

  switch(video){
  case H263:
    break;
  case H263P:
    eccx->flags |= CODEC_FLAG_H263P_SLICE_STRUCT;
    break;
  case H264:
    av_dict_set(&options, "vprofile", "baseline", 0);
    eccx->flags2 = CODEC_FLAG2_FASTPSKIP;
    eccx->profile = FF_PROFILE_H264_BASELINE;
    eccx->level = 13;
    break;
  }

When I execute this program I got the following output from libx264:

[libx264 @ 0x10fad60] using cpu capabilities: MMX2 SSE2Fast SSSE3 FastShuffle SSE4.1 Cache64
[libx264 @ 0x10fad60] profile Main, level 1.3

Why is this still Main profile, though I have set it explicitly to baseline?

Additionally, I would be really cool, if someone could add some notes which kind of h264 settings are useful for SIP phone calls. Thank you very much!

What is the VIDEO_FRAME_WIDTH and VIDEO_FRAME_HEIGHT? is it possible that these resolutions are too high? — Dundar
The profile is independent from the level. The level restricts the frame size. Level 1.3 allows frames up to CIF (en.wikipedia.org/wiki/H264#Levels). The input video stream has CIF. The input video might contain B-frames, which aren't allowed in Baseline, but how do I convince libav to convert them into I- or P- frames? — Denis Loh

nalply nalply · Accepted Answer · 2015-04-14T13:46:20

You should set options on the private part of the codec context:

av_opt_set(eccx->priv_data, "profile", "baseline", 0);

of course assuming that eccx is an AVCodecContext instance. Then open the codec with

avcodec_open2(eccx, codec, NULL);

where codec is your AVCodec instance which you should already have gotten with something similar to this:

AVCodec *codec = avcodec_find_encoder(AV_CODEC_ID_H264);

You can check that this works by giving an invalid profile name, then the library will tell you the valid profile names on standard error.

How to set x264 baseline profile with libav in C++

2 Answers