if (st->codec->codec_id == CODEC_ID_MP3) {
url_fskip(pb, 4);
av_get_packet(pb, pkt, len-4);
} else { // ADPCM, PCM
av_get_packet(pb, pkt, len);
}
if (st->codec->codec_id == CODEC_ID_MP3) {
url_fskip(pb, 4);
av_get_packet(pb, pkt, len-4);
} else { // ADPCM, PCM
av_get_packet(pb, pkt, len);
}