/********** 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 .) 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., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA **********/ // "liveMedia" // Copyright (c) 1996-2015 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, Boolean leavePresentationTimesUnmodified) { // Need to add source type checking here??? ##### return new MPEG1or2VideoStreamDiscreteFramer(env, inputSource, iFramesOnly, vshPeriod, leavePresentationTimesUnmodified); } MPEG1or2VideoStreamDiscreteFramer ::MPEG1or2VideoStreamDiscreteFramer(UsageEnvironment& env, FramedSource* inputSource, Boolean iFramesOnly, double vshPeriod, Boolean leavePresentationTimesUnmodified) : MPEG1or2VideoStreamFramer(env, inputSource, iFramesOnly, vshPeriod, False/*don't create a parser*/), fLeavePresentationTimesUnmodified(leavePresentationTimesUnmodified), fLastNonBFrameTemporal_reference(0), fSavedVSHSize(0), fSavedVSHTimestamp(0.0), fIFramesOnly(iFramesOnly), fVSHPeriod(vshPeriod) { 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 }; #define MILLION 1000000 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]; } // Also, save away this Video Sequence Header, in case we need it later: // First, figure out how big it is: unsigned vshSize; for (vshSize = 4; vshSize < frameSize-3; ++vshSize) { if (fTo[vshSize] == 0 && fTo[vshSize+1] == 0 && fTo[vshSize+2] == 1 && (fTo[vshSize+3] == 0xB8 || fTo[vshSize+3] == 0x00)) break; } if (vshSize == frameSize-3) vshSize = frameSize; // There was nothing else following it if (vshSize <= sizeof fSavedVSHBuffer) { memmove(fSavedVSHBuffer, fTo, vshSize); fSavedVSHSize = vshSize; fSavedVSHTimestamp = presentationTime.tv_sec + presentationTime.tv_usec/(double)MILLION; } } else if (nextCode == 0xB8) { // GROUP_START_CODE // If necessary, insert a saved Video Sequence Header in front of this: double pts = presentationTime.tv_sec + presentationTime.tv_usec/(double)MILLION; if (pts > fSavedVSHTimestamp + fVSHPeriod && fSavedVSHSize + frameSize <= fMaxSize) { memmove(&fTo[fSavedVSHSize], &fTo[0], frameSize); // make room for the header memmove(&fTo[0], fSavedVSHBuffer, fSavedVSHSize); // insert it frameSize += fSavedVSHSize; fSavedVSHTimestamp = pts; } } 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 not an "I" frame, but we were asked for "I" frames only, then try again: if (fIFramesOnly && picture_coding_type != 1) { doGetNextFrame(); return; } // If this is a "B" frame, then we have to tweak "presentationTime": if (!fLeavePresentationTimesUnmodified && 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 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 // Complete delivery to the client: fFrameSize = frameSize; fNumTruncatedBytes = numTruncatedBytes; fPresentationTime = presentationTime; fDurationInMicroseconds = durationInMicroseconds; afterGetting(this); }