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/**********
This library is free software; you can redistribute it and/or modify it under
the terms of the GNU Lesser General Public License as published by the
Free Software Foundation; either version 2.1 of the License, or (at your
option) any later version. (See <http://www.gnu.org/copyleft/lesser.html>.)
This library is distributed in the hope that it will be useful, but WITHOUT
ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS
FOR A PARTICULAR PURPOSE. See the GNU Lesser General Public License for
more details.
You should have received a copy of the GNU Lesser General Public License
along with this library; if not, write to the Free Software Foundation, Inc.,
59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
**********/
// "liveMedia"
// Copyright (c) 1996-2004 Live Networks, Inc. All rights reserved.
// A simplified version of "MPEG1or2VideoStreamFramer" that takes only
// complete, discrete frames (rather than an arbitrary byte stream) as input.
// This avoids the parsing and data copying overhead of the full
// "MPEG1or2VideoStreamFramer".
// Implementation
#include "MPEG1or2VideoStreamDiscreteFramer.hh"
MPEG1or2VideoStreamDiscreteFramer*
MPEG1or2VideoStreamDiscreteFramer::createNew(UsageEnvironment& env,
FramedSource* inputSource,
Boolean iFramesOnly,
double vshPeriod) {
// Need to add source type checking here??? #####
return new MPEG1or2VideoStreamDiscreteFramer(env, inputSource,
iFramesOnly, vshPeriod);
}
MPEG1or2VideoStreamDiscreteFramer
::MPEG1or2VideoStreamDiscreteFramer(UsageEnvironment& env,
FramedSource* inputSource,
Boolean iFramesOnly, double vshPeriod)
: MPEG1or2VideoStreamFramer(env, inputSource, iFramesOnly, vshPeriod,
False/*don't create a parser*/),
fLastNonBFrameTemporal_reference(0) {
fLastNonBFramePresentationTime.tv_sec = 0;
fLastNonBFramePresentationTime.tv_usec = 0;
}
MPEG1or2VideoStreamDiscreteFramer::~MPEG1or2VideoStreamDiscreteFramer() {
}
void MPEG1or2VideoStreamDiscreteFramer::doGetNextFrame() {
// Arrange to read data (which should be a complete MPEG-1 or 2 video frame)
// from our data source, directly into the client's input buffer.
// After reading this, we'll do some parsing on the frame.
fInputSource->getNextFrame(fTo, fMaxSize,
afterGettingFrame, this,
FramedSource::handleClosure, this);
}
void MPEG1or2VideoStreamDiscreteFramer
::afterGettingFrame(void* clientData, unsigned frameSize,
unsigned numTruncatedBytes,
struct timeval presentationTime,
unsigned durationInMicroseconds) {
MPEG1or2VideoStreamDiscreteFramer* source
= (MPEG1or2VideoStreamDiscreteFramer*)clientData;
source->afterGettingFrame1(frameSize, numTruncatedBytes,
presentationTime, durationInMicroseconds);
}
static double const frameRateFromCode[] = {
0.0, // forbidden
24000/1001.0, // approx 23.976
24.0,
25.0,
30000/1001.0, // approx 29.97
30.0,
50.0,
60000/1001.0, // approx 59.94
60.0,
0.0, // reserved
0.0, // reserved
0.0, // reserved
0.0, // reserved
0.0, // reserved
0.0, // reserved
0.0 // reserved
};
void MPEG1or2VideoStreamDiscreteFramer
::afterGettingFrame1(unsigned frameSize, unsigned numTruncatedBytes,
struct timeval presentationTime,
unsigned durationInMicroseconds) {
// Check that the first 4 bytes are a system code:
if (frameSize >= 4 && fTo[0] == 0 && fTo[1] == 0 && fTo[2] == 1) {
fPictureEndMarker = True; // Assume that we have a complete 'picture' here
u_int8_t nextCode = fTo[3];
if (nextCode == 0xB3) { // VIDEO_SEQUENCE_HEADER_START_CODE
// Note the following 'frame rate' code:
if (frameSize >= 8) {
u_int8_t frame_rate_code = fTo[7]&0x0F;
fFrameRate = frameRateFromCode[frame_rate_code];
}
}
unsigned i = 3;
if (nextCode == 0xB3 /*VIDEO_SEQUENCE_HEADER_START_CODE*/ ||
nextCode == 0xB8 /*GROUP_START_CODE*/) {
// Skip to the following PICTURE_START_CODE (if any):
for (i += 4; i < frameSize; ++i) {
if (fTo[i] == 0x00 /*PICTURE_START_CODE*/
&& fTo[i-1] == 1 && fTo[i-2] == 0 && fTo[i-3] == 0) {
nextCode = fTo[i];
break;
}
}
}
if (nextCode == 0x00 /*PICTURE_START_CODE*/ && i+2 < frameSize) {
// Get the 'temporal_reference' and 'picture_coding_type' from the
// following 2 bytes:
++i;
unsigned short temporal_reference = (fTo[i]<<2)|(fTo[i+1]>>6);
unsigned char picture_coding_type = (fTo[i+1]&0x38)>>3;
// If this is a "B" frame, then we have to tweak "presentationTime":
if (picture_coding_type == 3/*B*/
&& (fLastNonBFramePresentationTime.tv_usec > 0 ||
fLastNonBFramePresentationTime.tv_sec > 0)) {
int trIncrement
= fLastNonBFrameTemporal_reference - temporal_reference;
if (trIncrement < 0) trIncrement += 1024; // field is 10 bits in size
unsigned const MILLION = 1000000;
unsigned usIncrement = fFrameRate == 0.0 ? 0
: (unsigned)((trIncrement*MILLION)/fFrameRate);
unsigned secondsToSubtract = usIncrement/MILLION;
unsigned uSecondsToSubtract = usIncrement%MILLION;
presentationTime = fLastNonBFramePresentationTime;
if ((unsigned)presentationTime.tv_usec < uSecondsToSubtract) {
presentationTime.tv_usec += MILLION;
if (presentationTime.tv_sec > 0) --presentationTime.tv_sec;
}
presentationTime.tv_usec -= uSecondsToSubtract;
if ((unsigned)presentationTime.tv_sec > secondsToSubtract) {
presentationTime.tv_sec -= secondsToSubtract;
} else {
presentationTime.tv_sec = presentationTime.tv_usec = 0;
}
} else {
fLastNonBFramePresentationTime = presentationTime;
fLastNonBFrameTemporal_reference = temporal_reference;
}
}
}
// ##### Later:
// - do "iFramesOnly" if requested
// - handle "vshPeriod"
// Complete delivery to the client:
fFrameSize = frameSize;
fNumTruncatedBytes = numTruncatedBytes;
fPresentationTime = presentationTime;
fDurationInMicroseconds = durationInMicroseconds;
afterGetting(this);
}
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