avcodec_open2 error -542398533 : "Generic error in an external library"

Question

I am encountering an error when trying to open the codec with avcodec_open2(). I have tried the same code without any problems if I specify avi instead of h264 in the av_guess_format() function.

I don't know what to make of it. Has anyone else encountered a similar problem?

The library that I'm using is ffmpeg-20160219-git-98a0053-win32-dev. I would really really appreciate if you could help me out of this confusion.

This is my console output:

Video encoding
[libx264 @ 01383460] broken ffmpeg default settings detected
[libx264 @ 01383460] use an encoding preset (e.g. -vpre medium)
[libx264 @ 01383460] preset usage: -vpre -vpre
[libx264 @ 01383460] speed presets are listed in x264 --help
[libx264 @ 01383460] profile is optional; x264 defaults to high
Cannot open video codec, -542398533

This is the code that I'm working with:

// Video encoding sample
AVCodec *codec = NULL;
AVCodecContext *codecCtx= NULL;
AVFormatContext *pFormatCtx = NULL;
AVOutputFormat *pOutFormat = NULL;
AVStream * pVideoStream = NULL;;
AVFrame *picture = NULL;;

int i, x, y, ret;

printf("Video encoding\n");

// Register all formats and codecs
av_register_all();

// guess format from file extension
pOutFormat = av_guess_format("h264", NULL, NULL);
if (NULL==pOutFormat){
    cerr << "Could not guess output format" << endl;
    return -1;
}   

// allocate context
pFormatCtx = avformat_alloc_context();
pFormatCtx->oformat = pOutFormat;
memcpy(pFormatCtx->filename,filename,
    min(strlen(filename), sizeof(pFormatCtx->filename)));

// Add stream to pFormatCtx
pVideoStream = avformat_new_stream(pFormatCtx, 0);
if (!pVideoStream) 
{
    printf("Cannot add new video stream\n");
    return -1;
}

// Set stream's codec context
codecCtx = pVideoStream->codec;
codecCtx->codec_id = (AVCodecID)pOutFormat->video_codec;
codecCtx->codec_type = AVMEDIA_TYPE_VIDEO;
codecCtx->frame_number = 0;
// Put sample parameters.
codecCtx->bit_rate = 2000000;
// Resolution must be a multiple of two.
codecCtx->width  = 320;
codecCtx->height = 240;
codecCtx->time_base.den = 10;
codecCtx->time_base.num = 1;
pVideoStream->time_base.den = 10;
pVideoStream->time_base.num = 1;
codecCtx->gop_size = 12; // emit one intra frame every twelve frames at most
codecCtx->pix_fmt = AV_PIX_FMT_YUV420P;

if (codecCtx->codec_id == AV_CODEC_ID_H264)
{
    // Just for testing, we also add B frames 
    codecCtx->mb_decision = 2;
}
// Some formats want stream headers to be separate.
if(pFormatCtx->oformat->flags & AVFMT_GLOBALHEADER)
{
    codecCtx->flags |= CODEC_FLAG_GLOBAL_HEADER;
}

if(codecCtx->codec_id == AV_CODEC_ID_H264)
    av_opt_set(codecCtx->priv_data, "preset", "slow", 0);


// Open the codec.
codec = avcodec_find_encoder(codecCtx->codec_id);
if (codec == NULL) {
    fprintf(stderr, "Codec not found\n");
    return -1;
}
ret = avcodec_open2(codecCtx, codec, NULL); // returns -542398533 here
if (ret < 0) 
{
    printf("Cannot open video codec, %d\n",ret);
    return -1;
}

Ronald S. Bultje Ronald S. Bultje · Accepted Answer · 2016-03-24T13:40:36

Your problem is this line:

codecCtx = pVideoStream->codec;

This AVCodecContext was allocated using global defaults, which x264 rejects because they are not optimal. Instead, use avcodec_alloc_context3 to allocate it, which will set x264-specific defaults. At the end of your encoding, don't forget to avcodec_free_context the returned pointer.

avcodec_open2 error -542398533 : "Generic error in an external library"

2 Answers