unsigned MPEG1or2VideoStreamParser
::parseVideoSequenceHeader(Boolean haveSeenStartCode) {
#ifdef DEBUG
fprintf(stderr, "parsing video sequence header\n");
#endif
unsigned first4Bytes;
if (!haveSeenStartCode) {
while ((first4Bytes = test4Bytes()) != VIDEO_SEQUENCE_HEADER_START_CODE) {
#ifdef DEBUG
fprintf(stderr, "ignoring non video sequence header: 0x%08x\n", first4Bytes);
#endif
get1Byte(); setParseState(PARSING_VIDEO_SEQUENCE_HEADER);
// ensures we progress over bad data
}
first4Bytes = get4Bytes();
} else {
// We've already seen the start code
first4Bytes = VIDEO_SEQUENCE_HEADER_START_CODE;
}
save4Bytes(first4Bytes);
// Next, extract the size and rate parameters from the next 8 bytes
unsigned paramWord1 = get4Bytes();
save4Bytes(paramWord1);
unsigned next4Bytes = get4Bytes();
#ifdef DEBUG
unsigned short horizontal_size_value = (paramWord1&0xFFF00000)>>(32-12);
unsigned short vertical_size_value = (paramWord1&0x000FFF00)>>8;
unsigned char aspect_ratio_information = (paramWord1&0x000000F0)>>4;
#endif
unsigned char frame_rate_code = (paramWord1&0x0000000F);
usingSource()->fFrameRate = frameRateFromCode[frame_rate_code];
#ifdef DEBUG
unsigned bit_rate_value = (next4Bytes&0xFFFFC000)>>(32-18);
unsigned vbv_buffer_size_value = (next4Bytes&0x00001FF8)>>3;
fprintf(stderr, "horizontal_size_value: %d, vertical_size_value: %d, aspect_ratio_information: %d, frame_rate_code: %d (=>%f fps), bit_rate_value: %d (=>%d bps), vbv_buffer_size_value: %d\n", horizontal_size_value, vertical_size_value, aspect_ratio_information, frame_rate_code, usingSource()->fFrameRate, bit_rate_value, bit_rate_value*400, vbv_buffer_size_value);
#endif
// Now, copy all bytes that we see, up until we reach a GROUP_START_CODE
// or a PICTURE_START_CODE:
do {
saveToNextCode(next4Bytes);
} while (next4Bytes != GROUP_START_CODE && next4Bytes != PICTURE_START_CODE);
setParseState((next4Bytes == GROUP_START_CODE)
? PARSING_GOP_HEADER_SEEN_CODE : PARSING_PICTURE_HEADER);
// Compute this frame's timestamp by noting how many pictures we've seen
// since the last GOP header:
usingSource()->computePresentationTime(fPicturesSinceLastGOP);
// Save this video_sequence_header, in case we need to insert a copy
// into the stream later:
saveCurrentVSH();
return curFrameSize();
}
unsigned H264or5VideoStreamParser::parse() {
static int aaaa = 0 ;
aaaa++;
qDebug()<<"H264or5VideoStreamParser::parse() { 868 aaaa" <<aaaa;
try {
// The stream must start with a 0x00000001:
if (!fHaveSeenFirstStartCode) {
// Skip over any input bytes that precede the first 0x00000001:
u_int32_t first4Bytes;
while ((first4Bytes = test4Bytes()) != 0x00000001) {
get1Byte(); setParseState(); // ensures that we progress over bad data
}
skipBytes(4); // skip this initial code
setParseState();
fHaveSeenFirstStartCode = True; // from now on
}
if (fOutputStartCodeSize > 0 && curFrameSize() == 0 && !haveSeenEOF()) {
// Include a start code in the output:
save4Bytes(0x00000001);
}
// Then save everything up until the next 0x00000001 (4 bytes) or 0x000001 (3 bytes), or we hit EOF.
// Also make note of the first byte, because it contains the "nal_unit_type":
if (haveSeenEOF()) {
// We hit EOF the last time that we tried to parse this data, so we know that any remaining unparsed data
// forms a complete NAL unit, and that there's no 'start code' at the end:
unsigned remainingDataSize = totNumValidBytes() - curOffset();
#ifdef DEBUG
unsigned const trailingNALUnitSize = remainingDataSize;
#endif
while (remainingDataSize > 0) {
u_int8_t nextByte = get1Byte();
if (!fHaveSeenFirstByteOfNALUnit) {
fFirstByteOfNALUnit = nextByte;
fHaveSeenFirstByteOfNALUnit = True;
}
saveByte(nextByte);
--remainingDataSize;
}
#ifdef DEBUG
if (fHNumber == 264) {
u_int8_t nal_ref_idc = (fFirstByteOfNALUnit&0x60)>>5;
u_int8_t nal_unit_type = fFirstByteOfNALUnit&0x1F;
fprintf(stderr, "Parsed trailing %d-byte NAL-unit (nal_ref_idc: %d, nal_unit_type: %d (\"%s\"))\n",
trailingNALUnitSize, nal_ref_idc, nal_unit_type, nal_unit_type_description_h264[nal_unit_type]);
} else { // 265
u_int8_t nal_unit_type = (fFirstByteOfNALUnit&0x7E)>>1;
fprintf(stderr, "Parsed trailing %d-byte NAL-unit (nal_unit_type: %d (\"%s\"))\n",
trailingNALUnitSize, nal_unit_type, nal_unit_type_description_h265[nal_unit_type]);
}
#endif
(void)get1Byte(); // forces another read, which will cause EOF to get handled for real this time
return 0;
} else {
unsigned MPEG1or2VideoStreamParser::parsePictureHeader()
{
#ifdef DEBUG
fprintf(stderr, "parsing picture header\n");
#endif
// Note that we've already read the PICTURE_START_CODE
// Next, extract the temporal reference from the next 4 bytes:
unsigned next4Bytes = get4Bytes();
unsigned short temporal_reference = (next4Bytes & 0xFFC00000) >> (32 - 10);
unsigned char picture_coding_type = (next4Bytes & 0x00380000) >> 19;
#ifdef DEBUG
unsigned short vbv_delay = (next4Bytes & 0x0007FFF8) >> 3;
fprintf(stderr, "temporal_reference: %d, picture_coding_type: %d, vbv_delay: %d\n", temporal_reference, picture_coding_type, vbv_delay);
#endif
fSkippingCurrentPicture = fIFramesOnly && picture_coding_type != 1;
if (fSkippingCurrentPicture)
{
// Skip all bytes that we see, up until we reach a slice_start_code:
do
{
skipToNextCode(next4Bytes);
}
while (!isSliceStartCode(next4Bytes));
}
else
{
// Save the PICTURE_START_CODE that we've already read:
save4Bytes(PICTURE_START_CODE);
// Copy all bytes that we see, up until we reach a slice_start_code:
do
{
saveToNextCode(next4Bytes);
}
while (!isSliceStartCode(next4Bytes));
}
setParseState(PARSING_SLICE);
fCurrentSliceNumber = next4Bytes & 0xFF;
// Record the temporal reference:
fCurPicTemporalReference = temporal_reference;
// Compute this frame's timestamp:
usingSource()->computePresentationTime(fCurPicTemporalReference);
if (fSkippingCurrentPicture)
{
return parse(); // try again, until we get a non-skipped frame
}
else
{
return curFrameSize();
}
}
unsigned MPEG4VideoStreamParser
::parseVisualObjectSequence(Boolean haveSeenStartCode) {
#ifdef DEBUG
fprintf(stderr, "parsing VisualObjectSequence\n");
#endif
usingSource()->startNewConfig();
u_int32_t first4Bytes;
if (!haveSeenStartCode) {
while ((first4Bytes = test4Bytes()) != VISUAL_OBJECT_SEQUENCE_START_CODE) {
#ifdef DEBUG
fprintf(stderr, "ignoring non VS header: 0x%08x\n", first4Bytes);
#endif
get1Byte(); setParseState(PARSING_VISUAL_OBJECT_SEQUENCE);
// ensures we progress over bad data
}
first4Bytes = get4Bytes();
} else {
// We've already seen the start code
first4Bytes = VISUAL_OBJECT_SEQUENCE_START_CODE;
}
save4Bytes(first4Bytes);
// The next byte is the "profile_and_level_indication":
u_int8_t pali = get1Byte();
#ifdef DEBUG
fprintf(stderr, "profile_and_level_indication: %02x\n", pali);
#endif
saveByte(pali);
usingSource()->fProfileAndLevelIndication = pali;
// Now, copy all bytes that we see, up until we reach
// a VISUAL_OBJECT_START_CODE:
u_int32_t next4Bytes = get4Bytes();
while (next4Bytes != VISUAL_OBJECT_START_CODE) {
saveToNextCode(next4Bytes);
}
setParseState(PARSING_VISUAL_OBJECT);
// Compute this frame's presentation time:
usingSource()->computePresentationTime(fTotalTicksSinceLastTimeCode);
// This header forms part of the 'configuration' information:
usingSource()->appendToNewConfig(fStartOfFrame, curFrameSize());
return curFrameSize();
}
unsigned MPEG4VideoStreamParser::parseVisualObject() {
#ifdef DEBUG
fprintf(stderr, "parsing VisualObject\n");
#endif
// Note that we've already read the VISUAL_OBJECT_START_CODE
save4Bytes(VISUAL_OBJECT_START_CODE);
// Next, extract the "visual_object_type" from the next 1 or 2 bytes:
u_int8_t nextByte = get1Byte(); saveByte(nextByte);
Boolean is_visual_object_identifier = (nextByte&0x80) != 0;
u_int8_t visual_object_type;
if (is_visual_object_identifier) {
#ifdef DEBUG
fprintf(stderr, "visual_object_verid: 0x%x; visual_object_priority: 0x%x\n", (nextByte&0x78)>>3, (nextByte&0x07));
#endif
nextByte = get1Byte(); saveByte(nextByte);
visual_object_type = (nextByte&0xF0)>>4;
} else {
unsigned H264VideoStreamParser::parse() {
try {
// The stream must start with a 0x00000001:
if (!fHaveSeenFirstStartCode) {
// Skip over any input bytes that precede the first 0x00000001:
u_int32_t first4Bytes;
while ((first4Bytes = test4Bytes()) != 0x00000001) {
get1Byte(); setParseState(); // ensures that we progress over bad data
}
skipBytes(4); // skip this initial code
setParseState();
fHaveSeenFirstStartCode = True; // from now on
}
if (fOutputStartCodeSize > 0 && curFrameSize() == 0 && !haveSeenEOF()) {
// Include a start code in the output:
save4Bytes(0x00000001);
}
// Then save everything up until the next 0x00000001 (4 bytes) or 0x000001 (3 bytes), or we hit EOF.
// Also make note of the first byte, because it contains the "nal_unit_type":
if (haveSeenEOF()) {
// We hit EOF the last time that we tried to parse this data, so we know that any remaining unparsed data
// forms a complete NAL unit, and that there's no 'start code' at the end:
unsigned remainingDataSize = totNumValidBytes() - curOffset();
#ifdef DEBUG
unsigned const trailingNALUnitSize = remainingDataSize;
#endif
while (remainingDataSize > 0) {
u_int8_t nextByte = get1Byte();
if (!fHaveSeenFirstByteOfNALUnit) {
fFirstByteOfNALUnit = nextByte;
fHaveSeenFirstByteOfNALUnit = True;
}
saveByte(nextByte);
--remainingDataSize;
}
#ifdef DEBUG
u_int8_t nal_ref_idc = (fFirstByteOfNALUnit&0x60)>>5;
u_int8_t nal_unit_type = fFirstByteOfNALUnit&0x1F;
fprintf(stderr, "Parsed trailing %d-byte NAL-unit (nal_ref_idc: %d, nal_unit_type: %d (\"%s\"))\n",
trailingNALUnitSize, nal_ref_idc, nal_unit_type, nal_unit_type_description[nal_unit_type]);
#endif
(void)get1Byte(); // forces another read, which will cause EOF to get handled for real this time
return 0;
} else {
u_int32_t next4Bytes = test4Bytes();
if (!fHaveSeenFirstByteOfNALUnit) {
fFirstByteOfNALUnit = next4Bytes>>24;
fHaveSeenFirstByteOfNALUnit = True;
}
while (next4Bytes != 0x00000001 && (next4Bytes&0xFFFFFF00) != 0x00000100) {
// We save at least some of "next4Bytes".
if ((unsigned)(next4Bytes&0xFF) > 1) {
// Common case: 0x00000001 or 0x000001 definitely doesn't begin anywhere in "next4Bytes", so we save all of it:
save4Bytes(next4Bytes);
skipBytes(4);
} else {
// Save the first byte, and continue testing the rest:
saveByte(next4Bytes>>24);
skipBytes(1);
}
setParseState(); // ensures forward progress
next4Bytes = test4Bytes();
}
// Assert: next4Bytes starts with 0x00000001 or 0x000001, and we've saved all previous bytes (forming a complete NAL unit).
// Skip over these remaining bytes, up until the start of the next NAL unit:
if (next4Bytes == 0x00000001) {
skipBytes(4);
} else {
skipBytes(3);
}
}
unsigned H264VideoStreamParser::parse() {
try {
// The stream must start with a 0x00000001:
if (!fHaveSeenFirstStartCode) {
// Skip over any input bytes that precede the first 0x00000001:
u_int32_t first4Bytes;
while ((first4Bytes = test4Bytes()) != 0x00000001) {
get1Byte(); setParseState(); // ensures that we progress over bad data
}
skipBytes(4); // skip this initial code
setParseState();
fHaveSeenFirstStartCode = True; // from now on
}
if (fOutputStartCodeSize > 0) {
// Include a start code in the output:
save4Bytes(0x00000001);
}
// Then save everything up until the next 0x00000001 (4 bytes) or 0x000001 (3 bytes), or we hit EOF.
// Also make note of the first byte, because it contains the "nal_unit_type":
if (haveSeenEOF()) {
// We hit EOF the last time that we tried to parse this data, so we know that any remaining unparsed data
// forms a complete NAL unit, and that there's no 'start code' at the end:
unsigned remainingDataSize = totNumValidBytes() - curOffset();
while (remainingDataSize > 0) {
saveByte(get1Byte());
--remainingDataSize;
}
if (!fHaveSeenFirstByteOfNALUnit) {
// There's no remaining NAL unit.
(void)get1Byte(); // forces another read, which will cause EOF to get handled for real this time
return 0;
}
#ifdef DEBUG
fprintf(stderr, "This NAL unit (%d bytes) ends with EOF\n", curFrameSize()-fOutputStartCodeSize);
#endif
} else {
u_int32_t next4Bytes = test4Bytes();
if (!fHaveSeenFirstByteOfNALUnit) {
fFirstByteOfNALUnit = next4Bytes>>24;
fHaveSeenFirstByteOfNALUnit = True;
}
while (next4Bytes != 0x00000001 && (next4Bytes&0xFFFFFF00) != 0x00000100) {
// We save at least some of "next4Bytes".
if ((unsigned)(next4Bytes&0xFF) > 1) {
// Common case: 0x00000001 or 0x000001 definitely doesn't begin anywhere in "next4Bytes", so we save all of it:
save4Bytes(next4Bytes);
skipBytes(4);
} else {
// Save the first byte, and continue testing the rest:
saveByte(next4Bytes>>24);
skipBytes(1);
}
setParseState(); // ensures forward progress
next4Bytes = test4Bytes();
}
// Assert: next4Bytes starts with 0x00000001 or 0x000001, and we've saved all previous bytes (forming a complete NAL unit).
// Skip over these remaining bytes, up until the start of the next NAL unit:
if (next4Bytes == 0x00000001) {
skipBytes(4);
} else {
skipBytes(3);
}
}
u_int8_t nal_ref_idc = (fFirstByteOfNALUnit&0x60)>>5;
u_int8_t nal_unit_type = fFirstByteOfNALUnit&0x1F;
fHaveSeenFirstByteOfNALUnit = False; // for the next NAL unit that we parse
#ifdef DEBUG
fprintf(stderr, "Parsed %d-byte NAL-unit (nal_ref_idc: %d, nal_unit_type: %d (\"%s\"))\n",
curFrameSize()-fOutputStartCodeSize, nal_ref_idc, nal_unit_type, nal_unit_type_description[nal_unit_type]);
#endif
switch (nal_unit_type) {
case 6: { // Supplemental enhancement information (SEI)
analyze_sei_data();
// Later, perhaps adjust "fPresentationTime" if we saw a "pic_timing" SEI payload??? #####
break;
}
case 7: { // Sequence parameter set
// First, save a copy of this NAL unit, in case the downstream object wants to see it:
usingSource()->saveCopyOfSPS(fStartOfFrame + fOutputStartCodeSize, fTo - fStartOfFrame - fOutputStartCodeSize);
// Parse this NAL unit to check whether frame rate information is present:
unsigned num_units_in_tick, time_scale, fixed_frame_rate_flag;
analyze_seq_parameter_set_data(num_units_in_tick, time_scale, fixed_frame_rate_flag);
if (time_scale > 0 && num_units_in_tick > 0) {
usingSource()->fFrameRate = time_scale/(2.0*num_units_in_tick);
#ifdef DEBUG
fprintf(stderr, "Set frame rate to %f fps\n", usingSource()->fFrameRate);
if (fixed_frame_rate_flag == 0) {
fprintf(stderr, "\tWARNING: \"fixed_frame_rate_flag\" was not set\n");
}
#endif
} else {
#ifdef DEBUG
fprintf(stderr, "\tThis \"Sequence Parameter Set\" NAL unit contained no frame rate information, so we use a default frame rate of %f fps\n", usingSource()->fFrameRate);
#endif
}
break;
}
case 8: { // Picture parameter set
// Save a copy of this NAL unit, in case the downstream object wants to see it:
usingSource()->saveCopyOfPPS(fStartOfFrame + fOutputStartCodeSize, fTo - fStartOfFrame - fOutputStartCodeSize);
}
}
usingSource()->setPresentationTime();
#ifdef DEBUG
unsigned long secs = (unsigned long)usingSource()->fPresentationTime.tv_sec;
unsigned uSecs = (unsigned)usingSource()->fPresentationTime.tv_usec;
fprintf(stderr, "\tPresentation time: %lu.%06u\n", secs, uSecs);
#endif
// If this NAL unit is a VCL NAL unit, we also scan the start of the next NAL unit, to determine whether this NAL unit
// ends the current 'access unit'. We need this information to figure out when to increment "fPresentationTime".
// (RTP streamers also need to know this in order to figure out whether or not to set the "M" bit.)
Boolean thisNALUnitEndsAccessUnit = False; // until we learn otherwise
if (haveSeenEOF()) {
// There is no next NAL unit, so we assume that this one ends the current 'access unit':
thisNALUnitEndsAccessUnit = True;
} else {
Boolean const isVCL = nal_unit_type <= 5 && nal_unit_type > 0; // Would need to include type 20 for SVC and MVC #####
if (isVCL) {
u_int32_t first4BytesOfNextNALUnit = test4Bytes();
u_int8_t firstByteOfNextNALUnit = first4BytesOfNextNALUnit>>24;
u_int8_t next_nal_ref_idc = (firstByteOfNextNALUnit&0x60)>>5;
u_int8_t next_nal_unit_type = firstByteOfNextNALUnit&0x1F;
if (next_nal_unit_type >= 6) {
// The next NAL unit is not a VCL; therefore, we assume that this NAL unit ends the current 'access unit':
#ifdef DEBUG
fprintf(stderr, "\t(The next NAL unit is not a VCL)\n");
#endif
thisNALUnitEndsAccessUnit = True;
} else {
// The next NAL unit is also a VCL. We need to examine it a little to figure out if it's a different 'access unit'.
// (We use many of the criteria described in section 7.4.1.2.4 of the H.264 specification.)
Boolean IdrPicFlag = nal_unit_type == 5;
Boolean next_IdrPicFlag = next_nal_unit_type == 5;
if (next_IdrPicFlag != IdrPicFlag) {
// IdrPicFlag differs in value
#ifdef DEBUG
fprintf(stderr, "\t(IdrPicFlag differs in value)\n");
#endif
thisNALUnitEndsAccessUnit = True;
} else if (next_nal_ref_idc != nal_ref_idc && next_nal_ref_idc*nal_ref_idc == 0) {
// nal_ref_idc differs in value with one of the nal_ref_idc values being equal to 0
#ifdef DEBUG
fprintf(stderr, "\t(nal_ref_idc differs in value with one of the nal_ref_idc values being equal to 0)\n");
#endif
thisNALUnitEndsAccessUnit = True;
} else if ((nal_unit_type == 1 || nal_unit_type == 2 || nal_unit_type == 5)
&& (next_nal_unit_type == 1 || next_nal_unit_type == 2 || next_nal_unit_type == 5)) {
// Both this and the next NAL units begin with a "slice_header".
// Parse this (for each), to get parameters that we can compare:
// Current NAL unit's "slice_header":
unsigned frame_num, pic_parameter_set_id, idr_pic_id;
Boolean field_pic_flag, bottom_field_flag;
analyze_slice_header(fStartOfFrame + fOutputStartCodeSize, fTo, nal_unit_type,
frame_num, pic_parameter_set_id, idr_pic_id, field_pic_flag, bottom_field_flag);
// Next NAL unit's "slice_header":
#ifdef DEBUG
fprintf(stderr, " Next NAL unit's slice_header:\n");
#endif
u_int8_t next_slice_header[NUM_NEXT_SLICE_HEADER_BYTES_TO_ANALYZE];
testBytes(next_slice_header, sizeof next_slice_header);
unsigned next_frame_num, next_pic_parameter_set_id, next_idr_pic_id;
Boolean next_field_pic_flag, next_bottom_field_flag;
analyze_slice_header(next_slice_header, &next_slice_header[sizeof next_slice_header], next_nal_unit_type,
next_frame_num, next_pic_parameter_set_id, next_idr_pic_id, next_field_pic_flag, next_bottom_field_flag);
if (next_frame_num != frame_num) {
// frame_num differs in value
#ifdef DEBUG
fprintf(stderr, "\t(frame_num differs in value)\n");
#endif
thisNALUnitEndsAccessUnit = True;
} else if (next_pic_parameter_set_id != pic_parameter_set_id) {
// pic_parameter_set_id differs in value
#ifdef DEBUG
fprintf(stderr, "\t(pic_parameter_set_id differs in value)\n");
#endif
thisNALUnitEndsAccessUnit = True;
} else if (next_field_pic_flag != field_pic_flag) {
// field_pic_flag differs in value
#ifdef DEBUG
fprintf(stderr, "\t(field_pic_flag differs in value)\n");
#endif
thisNALUnitEndsAccessUnit = True;
} else if (next_bottom_field_flag != bottom_field_flag) {
// bottom_field_flag differs in value
#ifdef DEBUG
fprintf(stderr, "\t(bottom_field_flag differs in value)\n");
#endif
thisNALUnitEndsAccessUnit = True;
} else if (next_IdrPicFlag == 1 && next_idr_pic_id != idr_pic_id) {
// IdrPicFlag is equal to 1 for both and idr_pic_id differs in value
// Note: We already know that IdrPicFlag is the same for both.
#ifdef DEBUG
fprintf(stderr, "\t(IdrPicFlag is equal to 1 for both and idr_pic_id differs in value)\n");
#endif
thisNALUnitEndsAccessUnit = True;
}
}
}
}
}
if (thisNALUnitEndsAccessUnit) {
#ifdef DEBUG
fprintf(stderr, "*****This NAL unit ends the current access unit*****\n");
#endif
usingSource()->fPictureEndMarker = True;
++usingSource()->fPictureCount;
// Note that the presentation time for the next NAL unit will be different:
struct timeval& nextPT = usingSource()->fNextPresentationTime; // alias
nextPT = usingSource()->fPresentationTime;
double nextFraction = nextPT.tv_usec/1000000.0 + 1/usingSource()->fFrameRate;
unsigned nextSecsIncrement = (long)nextFraction;
nextPT.tv_sec += (long)nextSecsIncrement;
nextPT.tv_usec = (long)((nextFraction - nextSecsIncrement)*1000000);
}
setParseState();
return curFrameSize();
} catch (int /*e*/) {
unsigned MPEG1or2VideoStreamParser::parseGOPHeader(Boolean haveSeenStartCode)
{
// First check whether we should insert a previously-saved
// 'video_sequence_header' here:
if (needToUseSavedVSH()) return useSavedVSH();
#ifdef DEBUG
fprintf(stderr, "parsing GOP header\n");
#endif
unsigned first4Bytes;
if (!haveSeenStartCode)
{
while ((first4Bytes = test4Bytes()) != GROUP_START_CODE)
{
#ifdef DEBUG
fprintf(stderr, "ignoring non GOP start code: 0x%08x\n", first4Bytes);
#endif
get1Byte();
setParseState(PARSING_GOP_HEADER);
// ensures we progress over bad data
}
first4Bytes = get4Bytes();
}
else
{
// We've already seen the GROUP_START_CODE
first4Bytes = GROUP_START_CODE;
}
save4Bytes(first4Bytes);
// Next, extract the (25-bit) time code from the next 4 bytes:
unsigned next4Bytes = get4Bytes();
unsigned time_code = (next4Bytes & 0xFFFFFF80) >> (32 - 25);
#if defined(DEBUG) || defined(DEBUG_TIMESTAMPS)
Boolean drop_frame_flag = (time_code & 0x01000000) != 0;
#endif
unsigned time_code_hours = (time_code & 0x00F80000) >> 19;
unsigned time_code_minutes = (time_code & 0x0007E000) >> 13;
unsigned time_code_seconds = (time_code & 0x00000FC0) >> 6;
unsigned time_code_pictures = (time_code & 0x0000003F);
#if defined(DEBUG) || defined(DEBUG_TIMESTAMPS)
fprintf(stderr, "time_code: 0x%07x, drop_frame %d, hours %d, minutes %d, seconds %d, pictures %d\n", time_code, drop_frame_flag, time_code_hours, time_code_minutes, time_code_seconds, time_code_pictures);
#endif
#ifdef DEBUG
Boolean closed_gop = (next4Bytes & 0x00000040) != 0;
Boolean broken_link = (next4Bytes & 0x00000020) != 0;
fprintf(stderr, "closed_gop: %d, broken_link: %d\n", closed_gop, broken_link);
#endif
// Now, copy all bytes that we see, up until we reach a PICTURE_START_CODE:
do
{
saveToNextCode(next4Bytes);
}
while (next4Bytes != PICTURE_START_CODE);
// Record the time code:
usingSource()->setTimeCode(time_code_hours, time_code_minutes,
time_code_seconds, time_code_pictures,
fPicturesSinceLastGOP);
fPicturesSinceLastGOP = 0;
// Compute this frame's timestamp:
usingSource()->computePresentationTime(0);
setParseState(PARSING_PICTURE_HEADER);
return curFrameSize();
}
