+ if (!avctx->extradata || avctx->extradata_size < 12) {
+ av_log(avctx, AV_LOG_ERROR, "Missing or incomplete extradata\n");
+ return AVERROR_INVALIDDATA;
+ }
+ avctx->channels = AV_RB32(avctx->extradata ) + 1;
+ avctx->bit_rate = AV_RB32(avctx->extradata + 4) * 1000;
+ isampf = AV_RB32(avctx->extradata + 8);
+ switch (isampf) {
+ case 44: avctx->sample_rate = 44100; break;
+ case 22: avctx->sample_rate = 22050; break;
+ case 11: avctx->sample_rate = 11025; break;
+ default: avctx->sample_rate = isampf * 1000; break;
+ }
+
+ if (avctx->channels > CHANNELS_MAX) {