Function hb_ffmpeg_read

libhb/stream.c:6387–6579

}

hb_buffer_t * hb_ffmpeg_read( hb_stream_t *stream )
{
    int err;
    hb_buffer_t * buf;

  again:
    if ( ( err = av_read_frame( stream->ffmpeg_ic, stream->ffmpeg_pkt )) < 0 )
    {
        // av_read_frame can return EAGAIN.  In this case, it expects
        // to be called again to get more data.
        if ( err == AVERROR(EAGAIN) )
        {
            goto again;
        }
        // XXX the following conditional is to handle avi files that
        // use M$ 'packed b-frames' and occasionally have negative
        // sizes for the null frames these require.
        if ( err != AVERROR(ENOMEM) || stream->ffmpeg_pkt->size >= 0 )
        {
            // error or eof
            if (err != AVERROR_EOF)
            {
                char errstr[80];
                av_strerror(err, errstr, 80);
                hb_error("av_read_frame error (%d): %s", err, errstr);
                hb_set_work_error(stream->h, HB_ERROR_READ);
            }
            return NULL;
        }
    }
    if ( stream->ffmpeg_pkt->stream_index == stream->ffmpeg_video_id )
    {
        if ( stream->need_keyframe )
        {
            // we've just done a seek (generally for scan or live preview) and
            // want to start at a keyframe. Some ffmpeg codecs seek to a key
            // frame but most don't. So we spin until we either get a keyframe
            // or we've looked through 50 video frames without finding one.
            if ( ! ffmpeg_is_keyframe( stream ) && ++stream->need_keyframe < 50 )
            {
                av_packet_unref(stream->ffmpeg_pkt);
                goto again;
            }
            stream->need_keyframe = 0;
        }
        ++stream->frames;
    }
    AVStream *s = stream->ffmpeg_ic->streams[stream->ffmpeg_pkt->stream_index];
    if ( stream->ffmpeg_pkt->size <= 0 )
    {
        // M$ "invalid and inefficient" packed b-frames require 'null frames'
        // following them to preserve the timing (since the packing puts two
        // or more frames in what looks like one avi frame). The contents and
        // size of these null frames are ignored by the ff_h263_decode_frame
        // as long as they're < 20 bytes. Zero length buffers are also
        // use by theora to indicate duplicate frames.
        buf = hb_buffer_init( 0 );
    }