avcodec/adpcm_ima_amv: document header format

Zane van Iperen committed 6 years ago

Commit 8903cb31 parent 50d3a751 file · +10 −0Browse files

Unified · Split

libavcodec/adpcm.c+10−0

@@ -1690,6 +1690,16 @@ static int adpcm_decode_frame(AVCodecContext avctx, void data, · 1689 unmodified lines
1690	case AV_CODEC_ID_ADPCM_IMA_AMV:	1690	case AV_CODEC_ID_ADPCM_IMA_AMV:
1691	av_assert0(avctx->channels == 1);	1691	av_assert0(avctx->channels == 1);
1692		1692
		1693	/*
		1694	* Header format:
		1695	* int16_t predictor;
		1696	* uint8_t step_index;
		1697	* uint8_t reserved;
		1698	* uint32_t frame_size;
		1699	*
		1700	* Some implementations have step_index as 16-bits, but others
		1701	* only use the lower 8 and store garbage in the upper 8.
		1702	*/
1693	c->status[0].predictor = sign_extend(bytestream2_get_le16u(&gb), 16);	1703	c->status[0].predictor = sign_extend(bytestream2_get_le16u(&gb), 16);
1694	c->status[0].step_index = bytestream2_get_byteu(&gb);	1704	c->status[0].step_index = bytestream2_get_byteu(&gb);
1695	bytestream2_skipu(&gb, 5);	1705	bytestream2_skipu(&gb, 5);