avctx->bits_per_coded_sample = av_get_bits_per_pixel(desc);
if(!avctx->codec_tag)
avctx->codec_tag = avcodec_pix_fmt_to_codec_tag(avctx->pix_fmt);
avctx->bits_per_coded_sample = av_get_bits_per_pixel(desc);
if(!avctx->codec_tag)
avctx->codec_tag = avcodec_pix_fmt_to_codec_tag(avctx->pix_fmt);