1 files changed, 110 insertions, 0 deletions
diff --git a/Src/aacdec/ADTSHeader.c b/Src/aacdec/ADTSHeader.c
new file mode 100644
index 00000000..8e683270
--- /dev/null
+++ b/Src/aacdec/ADTSHeader.c
@@ -0,0 +1,110 @@
+#include "ADTSHeader.h"
+#include <bfc/error.h>
+
+enum
+{
+	ADTS_NOT_PROTECTED=1,
+	ADTS_PROTECTED=0,
+	ADTS_SYNC = 0xFFF,
+	ADTS_MAIN = 0x00,
+	ADTS_LC = 0x01,
+	ADTS_SSR = 0x10,
+	ADTS_LTP = 0x11,
+};
+
+
+int nsaac_adts_parse(nsaac_adts_header_t header, const uint8_t *buffer)
+{
+	unsigned int syncword = (buffer[0] << 4) | (buffer[1] >> 4);
+	unsigned int layer;
+	unsigned int sample_rate_index;
+	if (syncword != ADTS_SYNC)
+		return NErr_LostSynchronization;
+
+	header->syncword = syncword;
+	header->id = (buffer[1] >> 3) & 1;
+	layer = (buffer[1] >> 1) & 3;
+	if (layer != 0)
+		return NErr_WrongFormat;
+	header->layer = layer;	
+	header->protection = (buffer[1]) & 1;
+	header->profile = (buffer[2] >> 6) & 3;
+	sample_rate_index = (buffer[2] >> 2) & 0xF;
+	if (sample_rate_index == 15)
+		return NErr_UnsupportedFormat; // might actually be OK if we can separately signal the sample rate
+
+	if (sample_rate_index > 13)
+		return NErr_Reserved;
+
+	header->sample_rate_index = sample_rate_index;
+	header->private_bit = (buffer[2] >> 1) & 1;
+	header->channel_configuration = ((buffer[2] & 1) << 2) | ((buffer[3] >> 6) & 3);
+	header->original = (buffer[3] >> 5) &1;
+	header->home = (buffer[3] >> 4) &1;
+
+	//copyright_identification_bit = (buffer[3] >> 3) & 1;
+	//copyright_identification_start = (buffer[3] >> 2) & 1;
+	header->frame_length = ((buffer[3] & 3) << 11) | (buffer[4]<<3) | ((buffer[5] >> 5) & 7);
+	header->buffer_fullness = ((buffer[5] & 0x1F) << 6) | (buffer[6] >> 2);
+	header->num_data_blocks = buffer[6]  & 3;
+	return NErr_Success;
+}
+
+
+static const unsigned int aac_sratetab[] =
+{
+	96000,
+	88200,
+	64000,
+	48000,
+	44100,
+	32000,
+	24000,
+	22050,
+	16000,
+	12000,
+	11025,
+	8000,
+	7350,
+};
+
+unsigned int nsaac_adts_get_samplerate(nsaac_adts_header_t header)
+{
+	return aac_sratetab[header->sample_rate_index];
+}
+
+int nsaac_adts_match(nsaac_adts_header_t header1, nsaac_adts_header_t header2)
+{
+	if (header1->id != header2->id)
+		return NErr_False;
+
+	if (header1->profile != header2->profile)
+		return NErr_False;
+
+	if (header1->sample_rate_index != header2->sample_rate_index)
+		return NErr_False;
+
+	if (header1->channel_configuration != header2->channel_configuration)
+		return NErr_False;
+
+	return NErr_True;
+}
+
+int nsaac_adts_get_channel_count(nsaac_adts_header_t header)
+{
+	switch(header->channel_configuration)
+	{
+	case 7:
+		return 8;
+	default:
+		return header->channel_configuration;
+	}
+}
+
+size_t nsaac_adts_get_header_size(nsaac_adts_header_t header)
+{
+	if (header->protection == ADTS_PROTECTED)
+		return 9;
+	else
+		return 7;
+}
+\ No newline at end of file