int64_t avcodec_guess_channel_layout(int nb_channels, enum CodecID codec_id, const char *fmt_name) { switch(nb_channels) { case 1: return AV_CH_LAYOUT_MONO; case 2: return AV_CH_LAYOUT_STEREO; case 3: return AV_CH_LAYOUT_SURROUND; case 4: return AV_CH_LAYOUT_QUAD; case 5: return AV_CH_LAYOUT_5POINT0; case 6: return AV_CH_LAYOUT_5POINT1; case 8: return AV_CH_LAYOUT_7POINT1; default: return 0; } }