/*----------------------------------------------------------------------
| IsIFrame
+---------------------------------------------------------------------*/
static bool
IsIFrame(AP4_Sample& sample, AP4_AvcSampleDescription* avc_desc) {
AP4_DataBuffer sample_data;
if (AP4_FAILED(sample.ReadData(sample_data))) {
return false;
}
const unsigned char* data = sample_data.GetData();
AP4_Size size = sample_data.GetDataSize();
while (size >= avc_desc->GetNaluLengthSize()) {
unsigned int nalu_length = 0;
if (avc_desc->GetNaluLengthSize() == 1) {
nalu_length = *data++;
--size;
} else if (avc_desc->GetNaluLengthSize() == 2) {
nalu_length = AP4_BytesToUInt16BE(data);
data += 2;
size -= 2;
} else if (avc_desc->GetNaluLengthSize() == 4) {
nalu_length = AP4_BytesToUInt32BE(data);
data += 4;
size -= 4;
} else {
return false;
}
if (nalu_length <= size) {
size -= nalu_length;
} else {
size = 0;
}
switch (*data & 0x1F) {
case 1: {
AP4_BitStream bits;
bits.WriteBytes(data+1, 8);
ReadGolomb(bits);
unsigned int slice_type = ReadGolomb(bits);
if (slice_type == 2 || slice_type == 7) {
return true;
} else {
return false; // only show first slice type
}
}
case 5:
return true;
}
data += nalu_length;
}
return false;
}
/*----------------------------------------------------------------------
| PrintSliceInfo
+---------------------------------------------------------------------*/
static void
PrintSliceInfo(const unsigned char* data)
{
AP4_BitStream bits;
bits.WriteBytes(data, 8);
ReadGolomb(bits);
unsigned int slice_type = ReadGolomb(bits);
const char* slice_type_name = AP4_AvcNalParser::SliceTypeName(slice_type);
if (slice_type_name == NULL) slice_type_name = "?";
printf(" slice=%d (%s)", slice_type, slice_type_name);
}
/*----------------------------------------------------------------------
| ReadGolomb
+---------------------------------------------------------------------*/
static unsigned int
ReadGolomb(AP4_BitStream& bits)
{
unsigned int leading_zeros = 0;
while (bits.ReadBit() == 0) {
leading_zeros++;
}
if (leading_zeros) {
return (1<<leading_zeros)-1+bits.ReadBits(leading_zeros);
} else {
return 0;
}
}