[Libav-user] convert MP4 frames to Annex B

[Selmeci, Tamas]

On Fri, 2014-07-18 at 14:59 +0200, Selmeci, Tamas wrote:

> Doing something like this simply doesn't filter the input buffer:
> 
> int out_size;
> uint8_t *out;
> AVPacket packet;
> AVCodec *codec;
> AVCodecContext *codec_ctx;
> AVBitStreamFilterContext *annexb;
> 
> annexb = av_bitstream_filter_init("h264_mp4toannexb");
> 
> av_read_frame(context, &packet);
> av_read_frame(context, &packet);
> ...
> codec = avcodec_find_decoder(AV_CODEC_ID_H264);
> codec_ctx = avcodec_alloc_context3(codec);
> avcodec_open2(codec_ctx, codec, NULL);
> av_bitstream_filter_filter(annexb,
>     codec_ctx,
>     NULL,
>     &out,
>     &out_size,
>     packet.data,
>     packet.size,
>     packet.flags & AV_PKT_FLAG_KEY);
> avcodec_close(codec_ctx);
> av_free(codec_ctx);
> av_bitstream_filter_close(annexb);

Okay, I've figured it out. The above is wrong, you don't have to create
a codec context, instead must use the codec context in
AVFormatContext::streams[idx]::codec. And it's now working perfectly ;)

Regards,
-- 
Selmeci, Tamás
http://www.open-st.eu/