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I am using a recent windows (Jan 2011) ffmpeg build and trying to record video in H264. It is recording fine in MPEG4 using the following settings:

c->codec_id = CODEC_ID_MPEG4;
c->codec_type = AVMEDIA_TYPE_VIDEO;
c->width = VIDEO_WIDTH;
c->height = VIDEO_HEIGHT;
c->bit_rate = c->width * c->height * 4;
c->time_base.den = FRAME_RATE;
c->time_base.num = 1;
c->gop_size = 12;
c->pix_fmt = PIX_FMT_YUV420P;

Simply changing CODEC Id to H264 causes avcodec_open() to fail (-1). I found a list of possible settings How to encode h.264 with libavcodec/x264?. I have tried these, without setting pix_fmt, avcodec_open() still fails but if I additionally set c->pix_fmt = PIX_FMT_YUV420P; then I get a divide by zero exception.

I then came across a few posts on here that say I should set nothing (with exception of code_id, codec_type, width, height and perhaps bit_rate and pix_fmt) as the library now chooses the best settings itself. I have tried various combinations, still avcode_open() fails.

Does anyone have some advice on what to do or some settings that are current?

Thanks.

Here are one set of H264 settings which give the issue I describe:

static AVStream* AddVideoStream(AVFormatContext *pOutputFmtCtx, 
int frameWidth, int frameHeight, int fps)
{
AVCodecContext* ctx;
AVStream* stream;

stream = av_new_stream(pOutputFmtCtx, 0);
if (!stream) 
{
    return NULL;
}

ctx = stream->codec;

ctx->codec_id = pOutputFmtCtx->oformat->video_codec; //CODEC_ID_H264
ctx->codec_type = AVMEDIA_TYPE_VIDEO;
ctx->width = frameWidth;             //704
ctx->height = frameHeight;           //576
ctx->bit_rate = frameWidth * frameHeight * 4;

ctx->coder_type = 1;  // coder = 1
ctx->flags|=CODEC_FLAG_LOOP_FILTER;   // flags=+loop
ctx->me_cmp|= 1;  // cmp=+chroma, where CHROMA = 1
ctx->partitions|=X264_PART_I8X8+X264_PART_I4X4+X264_PART_P8X8+X264_PART_B8X8; // partitions=+parti8x8+parti4x4+partp8x8+partb8x8
ctx->me_method=ME_HEX;    // me_method=hex
ctx->me_subpel_quality = 7;   // subq=7
ctx->me_range = 16;   // me_range=16
ctx->gop_size = 250;  // g=250
ctx->keyint_min = 25; // keyint_min=25
ctx->scenechange_threshold = 40;  // sc_threshold=40
ctx->i_quant_factor = 0.71; // i_qfactor=0.71
ctx->b_frame_strategy = 1;  // b_strategy=1
ctx->qcompress = 0.6; // qcomp=0.6
ctx->qmin = 10;   // qmin=10
ctx->qmax = 51;   // qmax=51
ctx->max_qdiff = 4;   // qdiff=4
ctx->max_b_frames = 3;    // bf=3
ctx->refs = 3;    // refs=3
ctx->directpred = 1;  // directpred=1
ctx->trellis = 1; // trellis=1
       ctx->flags2|=CODEC_FLAG2_BPYRAMID+CODEC_FLAG2_MIXED_REFS+CODEC_FLAG2_WPRED+CODEC_FLAG2_8X8DCT+CODEC_FLAG2_FASTPSKIP;  // flags2=+bpyramid+mixed_refs+wpred+dct8x8+fastpskip
ctx->weighted_p_pred = 2; // wpredp=2
// libx264-main.ffpreset preset
ctx->flags2|=CODEC_FLAG2_8X8DCT;
ctx->flags2^=CODEC_FLAG2_8X8DCT;    // flags2=-dct8x8

// if set this get divide by 0 error on avcodec_open()
// if don't set it get -1 error on avcodec_open()
//ctx->pix_fmt = PIX_FMT_YUV420P; 

return stream;

}

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integra753
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  • Are you sure the h.264 codec is included in the ffmpeg build? – ciphor Feb 07 '12 at 13:52
  • I am using http://ffmpeg.zeranoe.com/builds/ builds. they state it was built with --enable-libx264. – integra753 Feb 07 '12 at 15:57
  • Please post your code for CODEC_ID_H264 – ciphor Feb 08 '12 at 02:13
  • set the avcodeccontext avrational to correct value. – Sureshkumar Menon Mar 09 '12 at 07:23
  • I have exactly the same problem: - source downloaded from http://ffmpeg.zeranoe.com/builds/ - avcodec_open() returns -1 for CODEC_ID_H264 - avcodec_open() perfectly works for CODEC_ID_MPEG2VIDEO - ffmpeg.zeranoe.com/builds indicates that the libraries were built with --enable-libx264 So, have you find the solution? –  Oct 09 '12 at 23:14
  • @integra753 Please post your payloadType for H264. I means something like this: {34, "H263", AVMEDIA_TYPE_VIDEO, CODEC_ID_H263, 90000, -1} – Dr.jacky Oct 12 '15 at 07:53

1 Answers1

3

In my experience you should give FFMPEG the least amount of information when initialising your codec as possible. This may seem counter intuitive but it means that FFMPEG will use it's default settings that are more likely to work than your own guesses. See what I would include below:

AVStream *stream;
m_video_codec = avcodec_find_encoder(AV_CODEC_ID_H264);
stream = avformat_new_stream(_outputCodec, m_video_codec);
ctx = stream->codec;
ctx->codec_id = m_fmt->video_codec;
ctx->bit_rate = m_AVIMOV_BPS;           //Bits Per Second 
ctx->width    = m_AVIMOV_WIDTH;         //Note Resolution must be a multiple of 2!!
ctx->height   = m_AVIMOV_HEIGHT;        //Note Resolution must be a multiple of 2!!
ctx->time_base.den = m_AVIMOV_FPS;      //Frames per second
ctx->time_base.num = 1;
ctx->gop_size      = m_AVIMOV_GOB;      // Intra frames per x P frames
ctx->pix_fmt       = AV_PIX_FMT_YUV420P;//Do not change this, H264 needs YUV format not RGB

As in previous answers, here is a working example of the FFMPEG library encoding RGB frames to a H264 video:

http://www.imc-store.com.au/Articles.asp?ID=276

An extra thought on your code though:

  • Have you called register all like below?

    avcodec_register_all();

    av_register_all();

    If you don't call these two functions near the start of your code your subsequent calls to FFMPEG will fail and you'll most likely seg-fault.

Have a look at the linked example, I tested it on VC++2010 and it works perfectly.

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