- AV_WL16(st->codecpar->extradata, 1);
- AV_WL16(st->codecpar->extradata+4, 4096);
+ AV_WL16(st->codecpar->extradata, 1); /* version */
+ AV_WL16(st->codecpar->extradata+2, 2048 * st->codecpar->channels); /* unknown size */
+ AV_WL16(st->codecpar->extradata+6, codec == 4 ? 1 : 0); /* joint stereo */
+ AV_WL16(st->codecpar->extradata+8, codec == 4 ? 1 : 0); /* joint stereo (repeat?) */