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12 Feb 2007

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MadMP3Decoder Class Reference

Adaptor class MadMP3Decoder decodes bypassing MPEG-1/2 layer 3 audio packets to raw PCM sample blocks using the libmad <short description="">. More...

#include <MadMP3Decoder.hpp>

Inheritance diagram for MadMP3Decoder:

List of all members.

Public Member Functions
	MadMP3Decoder (AudioESInfo *es)
list< Frame * >	adapt (Frame *frm)
	Accepts as input a frame, and checks if it can adapt the frame, If the frame is modified, a new Frame object is created and inserted into the return list.
Adaptor *	clone ()
	Create a shallow copy of the Adaptor.
void	initialize ()
	Initialize internal data structures.
list< Frame * >	close ()
	Close and destroy an Adaptor.
u32	getTranscodingCosts () const
	returns adaptation costs (CPU only).
Static Protected Member Functions
signed short	MadFixedToSshort (mad_fixed_t Fixed)
void	PrintFrameInfo (struct mad_header *Header)
Protected Attributes
mad_stream	Stream
mad_frame	madFrame
mad_synth	Synth
mad_timer_t	Timer
unsigned char *	inputBuffer
unsigned char *	guardPtr
int	Status
unsigned long	FrameCount
u32	numInFrames
bool	initialized
u32	lastTS
AU *	pAU

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Detailed Description

Adaptor class MadMP3Decoder decodes bypassing MPEG-1/2 layer 3 audio packets to raw PCM sample blocks using the libmad <short description="">.

Author:

Michael Kropfberger

Version:

Id

MadMP3Decoder.hpp,v 1.3 2006/01/20 15:37:17 mkropfbe Exp

Definition at line 67 of file MadMP3Decoder.hpp.

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Member Function Documentation

list< Frame * > MadMP3Decoder::adapt (  Frame *  frm  )  [virtual]

Accepts as input a frame, and checks if it can adapt the frame, If the frame is modified, a new Frame object is created and inserted into the return list. This new frame is returned only, if the size of the payload is larger than zero. If the frame was not modified, it is also inserted into the list. For more complex adaptors, it will happen, that the adaptor caches up one complete GOP and returns the full GOP in network order. A caching adaptor has to create deep-copies for each frames. Never directly modify the payload of the input frm, always create copies!!! Parameters: frm  object to adapt. An Adaptor is never allowed to free the input frame. This has to be done in the caller. Returns: List of adapted Frame objects Reimplemented from Adaptor. Definition at line 89 of file MadMP3Decoder.cpp. References Frame::getAU(), Frame::getMediaTimeScale(), initialize(), Frame::setAU(), and Frame::setMediaTimeScale(). { list < Frame * >tmp; u32 thisCTS; int thisSec; //initialize decoder if (numInFrames == 0) { initialize(); } if (frm->getAU() == NULL) return tmp; thisCTS = frm->getAU()->cts; thisSec = (int)floor((double)thisCTS / es->getMediaTimeScale()); dprintf_full("MadMP3Decoder::adapt frame %i (size %i) CTS %i, VOP increment %i, samplerate %i Hz Channels: %i\n", numInFrames, frm->getAU()->size, thisCTS, es->getVOPTimeIncrement(), es->getSampleRate(), es->getAudioChannels()); numInFrames++; //FIXME: assert(isAudioFrame) assert(Stream.buffer==NULL || Stream.error==MAD_ERROR_BUFLEN); if(Stream.buffer==NULL || Stream.error==MAD_ERROR_BUFLEN) { size_t ReadSize, Remaining; unsigned char *ReadStart; if(Stream.next_frame!=NULL) { Remaining = Stream.bufend - Stream.next_frame; //dprintf_full("MadMP3Decoder::adapt ... pre-pend old data %i bytes (bufsize %i offs %i)\n",Remaining, Stream.bufend - inputBuffer, Stream.next_frame - inputBuffer); memmove(inputBuffer, Stream.next_frame, Remaining); //move to beginning ReadStart = inputBuffer+Remaining; //add new data behind old data ReadSize = MAD_INPUT_BUFFER_SIZE - Remaining; //space left } else { ReadSize = MAD_INPUT_BUFFER_SIZE; ReadStart = inputBuffer; Remaining = 0; } //dprintf_full("MadMP3Decoder::adapt ... adding incoming frame to decoding buffer (adding %i bytes)\n",frm->getAU()->size); assert( frm->getAU()->size <= ReadSize); memcpy(ReadStart, frm->getAU()->payload, frm->getAU()->size); ReadSize = (size_t)frm->getAU()->size; if(0==1 /* EOF */) { dprintf_full("MadMP3Decoder::adapt ... adding guard 8 zero bytes\n"); guardPtr=ReadStart+ReadSize; memset(guardPtr,0,MAD_BUFFER_GUARD); ReadSize+=MAD_BUFFER_GUARD; } /* Pipe the new buffer content to libmad's stream decoder * facility. */ mad_stream_buffer(&Stream, inputBuffer, ReadSize+Remaining); Stream.error=MAD_ERROR_NONE; } lastTS = thisCTS; pAU = new AU(frm->getAU()); pAU->cts = pAU->dts = lastTS; //we are always a little behind... //lastTS += (u32)((es->getMediaTimeScale()/(float)es->getSampleRate())*Synth.pcm.length); pAU->size = 0; u8 *outputBuffer = NULL; do { //dprintf_full("MadMP3Decoder::adapt ...decoding lastBufSize %i offs %i)\n",Stream.bufend - inputBuffer, Stream.next_frame - inputBuffer); if(mad_frame_decode(&madFrame, &Stream)) { if(MAD_RECOVERABLE(Stream.error)) { /* Do not print a message if the error is a loss of * synchronization and this loss is due to the end of * stream guard bytes. (See the comments marked {3} * supra for more informations about guard bytes.) */ if((Stream.error!=MAD_ERROR_LOSTSYNC) || (Stream.this_frame!=guardPtr)) { dprintf_err("MadMP3Decoder::adapt: recoverable frame level error (%s) at offs %i\n",mad_stream_errorstr(&Stream),Stream.next_frame-inputBuffer); } //lastTS += (u32)((es->getMediaTimeScale()/(float)es->getSampleRate())*1152); continue; } else if(Stream.error==MAD_ERROR_BUFLEN) { //this is not serious, just not enough data.... going into next round.... //dprintf_err("MadMP3Decoder::adapt: recoverable frame level error BUFLEN (%s) at offs %i\n",mad_stream_errorstr(&Stream),Stream.next_frame-inputBuffer); break; } else { dprintf_err("MadMP3Decoder::adapt: unrecoverable frame level error (%s).\n",mad_stream_errorstr(&Stream)); Status=1; ::exit(1); } } if(FrameCount==0) //the first is representative for all other frames PrintFrameInfo(&madFrame.header); FrameCount++; #ifndef WINCE mad_timer_add(&Timer,madFrame.header.duration); #endif mad_synth_frame(&Synth,&madFrame); //dprintf_full("MadMP3Decoder::adapt sampling %i raw pcm samples\n", Synth.pcm.length); //DO NOT SEND 1st FRAME (the header) to the audio-output #ifdef WINCE if (FrameCount == 1) { outputBuffer = NULL; } else { #endif u32 numChannels = es->getAudioChannels(); pAU->size += Synth.pcm.length * 2 * numChannels; //if it's 16bit stereo --> * 4 outputBuffer = (u8*)realloc(outputBuffer, pAU->size); //get more space, if necessary pAU->payload = outputBuffer; u8 *outputPtr = outputBuffer + pAU->size - Synth.pcm.length * 2 * numChannels; // begin of new block for(int i=0;i<Synth.pcm.length;i++) { signed short Sample; /* Left channel */ Sample=MadFixedToSshort(Synth.pcm.samples[0][i]); *(outputPtr++)=Sample&0xff; //little endian, so toggle *(outputPtr++)=Sample>>8; if (numChannels == 2) { //stereo /* Right channel. If the decoded stream is monophonic then * the right output channel is the same as the left one. */ if(MAD_NCHANNELS(&madFrame.header)==2) Sample=MadFixedToSshort(Synth.pcm.samples[1][i]); *(outputPtr++)=Sample&0xff; //little endian, so toggle *(outputPtr++)=Sample>>8; } } #ifdef WINCE } #endif } while(1); if (outputBuffer) { dprintf_full("MadMP3Decoder::adapt got full decoded (raw pcm) frame number %li (CTS %i) size %i bytes!\n", FrameCount, pAU->cts, pAU->size); UncompressedAudioFrame * decFrame = new UncompressedAudioFrame(Frame::RAW_AUDIO); decFrame->setAU(pAU); decFrame->setMediaTimeScale(frm->getMediaTimeScale()); tmp.push_back(decFrame); } return tmp; }

Adaptor* MadMP3Decoder::clone (   )  [inline, virtual]

Create a shallow copy of the Adaptor. Creates an Adaptor with the same setup (without copying the current status). Returns: An Adaptor object. Implements Adaptor. Definition at line 81 of file MadMP3Decoder.hpp. { return new MadMP3Decoder(es); };

list< Frame * > MadMP3Decoder::close (   )  [inline, virtual]

Close and destroy an Adaptor. Releases all internally buffered frame objects, and deallocate all allocated memory. The Adaptor must not be used after calling the close method!!! Returns: List of adapted Frame objects. Reimplemented from Adaptor. Definition at line 85 of file MadMP3Decoder.hpp. { list < Frame * >tmp; return tmp; };

u32 MadMP3Decoder::getTranscodingCosts (   )  const [inline, virtual]

returns adaptation costs (CPU only). This adaptor causes hd costs, which are currently ignored. as CPU side effect we can only guess but it should depend on the bytes of the video Implements Adaptor. Definition at line 95 of file MadMP3Decoder.hpp. { return es->getAvgBandwidth()/8; }

void MadMP3Decoder::initialize (   )  [virtual]

Initialize internal data structures. Implements Adaptor. Definition at line 71 of file MadMP3Decoder.cpp. Referenced by adapt(). { /* First the structures used by libmad must be initialized. */ mad_stream_init(&Stream); mad_frame_init(&madFrame); mad_synth_init(&Synth); #ifndef WINCE mad_timer_reset(&Timer); #endif guardPtr = NULL; initialized=true; numInFrames = 0; }

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The documentation for this class was generated from the following files:

• MadMP3Decoder.hpp
• MadMP3Decoder.cpp

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