/**
* Decode an array of 4 bit element IDs, optionally interleaved with a stereo/mono switching bit.
*
* @throws IOException
*/
private void decodeChannelMap(
ChannelMapping layout_map[], int offset, ChannelPosition type, InBits in, int n)
throws IOException {
while (n-- > 0) {
RawDataBlockType syn_ele = null;
switch (type) {
case AAC_CHANNEL_FRONT:
case AAC_CHANNEL_BACK:
case AAC_CHANNEL_SIDE:
syn_ele = RawDataBlockType.fromOrdinal(in.read1Bit());
break;
case AAC_CHANNEL_CC:
in.read1Bit();
syn_ele = RawDataBlockType.TYPE_CCE;
break;
case AAC_CHANNEL_LFE:
syn_ele = RawDataBlockType.TYPE_LFE;
break;
}
layout_map[offset].syn_ele = syn_ele;
layout_map[offset].someInt = (int) in.readNBit(4);
layout_map[offset].position = type;
offset++;
}
}
public void parse(InBits in) throws IOException {
in.readNBit(2); // object_type
int samplingIndex = (int) in.readNBit(4);
int num_front = (int) in.readNBit(4);
int num_side = (int) in.readNBit(4);
int num_back = (int) in.readNBit(4);
int num_lfe = (int) in.readNBit(2);
int num_assoc_data = (int) in.readNBit(3);
int num_cc = (int) in.readNBit(4);
if (in.read1Bit() != 0) in.readNBit(4); // mono_mixdown_tag
if (in.read1Bit() != 0) in.readNBit(4); // stereo_mixdown_tag
if (in.read1Bit() != 0) in.readNBit(3); // mixdown_coeff_index and pseudo_surround
// if (!in.moreData(4 * (num_front + num_side + num_back + num_lfe + num_assoc_data +
// num_cc))) {
// throw new RuntimeException("Overread");
// }
ChannelMapping[] layout_map = new ChannelMapping[MAX_ELEM_ID * 4];
int tags = 0;
decodeChannelMap(layout_map, tags, ChannelPosition.AAC_CHANNEL_FRONT, in, num_front);
tags = num_front;
decodeChannelMap(layout_map, tags, ChannelPosition.AAC_CHANNEL_SIDE, in, num_side);
tags += num_side;
decodeChannelMap(layout_map, tags, ChannelPosition.AAC_CHANNEL_BACK, in, num_back);
tags += num_back;
decodeChannelMap(layout_map, tags, ChannelPosition.AAC_CHANNEL_LFE, in, num_lfe);
tags += num_lfe;
in.skip(4 * num_assoc_data);
decodeChannelMap(layout_map, tags, ChannelPosition.AAC_CHANNEL_CC, in, num_cc);
tags += num_cc;
in.align();
/* comment field, first byte is length */
int comment_len = (int) in.readNBit(8) * 8;
// if (!in.moreData(comment_len)) {
// throw new RuntimeException("Overread");
// }
in.skip(comment_len);
}