ast->codec.channels = 2;
static int dv_read_header(AVFormatContext *s,                          AVFormatParameters *ap){    AVStream *vst, *ast;    DVDemuxContext *c = s->priv_data;    vst = av_new_stream(s, 0);    if (!vst)        return AVERROR_NOMEM;    vst->codec.codec_type = CODEC_TYPE_VIDEO;    vst->codec.codec_id = CODEC_ID_DVVIDEO;    ast = av_new_stream(s, 1);    if (!ast)        return AVERROR_NOMEM;    ast->codec.codec_type = CODEC_TYPE_AUDIO;    ast->codec.codec_id = CODEC_ID_DVAUDIO;    ast->codec.channels = 2;    c->is_audio = 0;    return 0;}