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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) 1996-2005 Live Networks, Inc. All rights reserved.
// A source object for AAC audio files in ADTS format
// Implementation
#include "ADTSAudioFileSource.hh"
#include "InputFile.hh"
#include <GroupsockHelper.hh>
////////// ADTSAudioFileSource //////////
static unsigned const samplingFrequencyTable[16] = {
96000, 88200, 64000, 48000,
44100, 32000, 24000, 22050,
16000, 12000, 11025, 8000,
7350, 0, 0, 0
};
ADTSAudioFileSource*
ADTSAudioFileSource::createNew(UsageEnvironment& env, char const* fileName) {
FILE* fid = NULL;
do {
fid = OpenInputFile(env, fileName);
if (fid == NULL) break;
// Now, having opened the input file, read the fixed header of the first frame,
// to get the audio stream's parameters:
unsigned char fixedHeader[4]; // it's actually 3.5 bytes long
if (fread(fixedHeader, 1, sizeof fixedHeader, fid) < sizeof fixedHeader) break;
// Check the 'syncword':
if (!(fixedHeader[0] == 0xFF && (fixedHeader[1]&0xF0) == 0xF0)) {
env.setResultMsg("Bad 'syncword' at start of ADTS file");
break;
}
// Get and check the 'profile':
u_int8_t profile = (fixedHeader[2]&0xC0)>>6; // 2 bits
if (profile == 3) {
env.setResultMsg("Bad (reserved) 'profile': 3 in first frame of ADTS file");
break;
}
// Get and check the 'sampling_frequency_index':
u_int8_t sampling_frequency_index = (fixedHeader[2]&0x3C)>>2; // 4 bits
if (samplingFrequencyTable[sampling_frequency_index] == 0) {
env.setResultMsg("Bad 'sampling_frequency_index' in first frame of ADTS file");
break;
}
// Get and check the 'channel_configuration':
u_int8_t channel_configuration
= ((fixedHeader[2]&0x01)<<2)|((fixedHeader[3]&0xC0)>>6); // 3 bits
// If we get here, the frame header was OK.
// Reset the fid to the beginning of the file:
rewind(fid);
#ifdef DEBUG
fprintf(stderr, "Read first frame: profile %d, "
"sampling_frequency_index %d => samplingFrequency %d, "
"channel_configuration %d\n",
profile,
sampling_frequency_index, samplingFrequencyTable[sampling_frequency_index],
channel_configuration);
#endif
return new ADTSAudioFileSource(env, fid, profile,
sampling_frequency_index, channel_configuration);
} while (0);
// An error occurred:
CloseInputFile(fid);
return NULL;
}
ADTSAudioFileSource
::ADTSAudioFileSource(UsageEnvironment& env, FILE* fid, u_int8_t profile,
u_int8_t samplingFrequencyIndex, u_int8_t channelConfiguration)
: FramedFileSource(env, fid) {
fSamplingFrequency = samplingFrequencyTable[samplingFrequencyIndex];
fNumChannels = channelConfiguration == 0 ? 2 : channelConfiguration;
fuSecsPerFrame
= (1024/*samples-per-frame*/*1000000) / fSamplingFrequency/*samples-per-second*/;
// Construct the 'AudioSpecificConfig', and from it, the corresponding ASCII string:
unsigned char audioSpecificConfig[2];
u_int8_t const audioObjectType = profile + 1;
audioSpecificConfig[0] = (audioObjectType<<3) | (samplingFrequencyIndex>>1);
audioSpecificConfig[1] = (samplingFrequencyIndex<<7) | (channelConfiguration<<3);
sprintf(fConfigStr, "%02X%02x", audioSpecificConfig[0], audioSpecificConfig[1]);
}
ADTSAudioFileSource::~ADTSAudioFileSource() {
CloseInputFile(fFid);
}
void ADTSAudioFileSource::doGetNextFrame() {
// Begin by reading the 7-byte fixed_variable headers:
unsigned char headers[7];
if (fread(headers, 1, sizeof headers, fFid) < sizeof headers
|| feof(fFid) || ferror(fFid)) {
// The input source has ended:
handleClosure(this);
return;
}
// Extract important fields from the headers:
Boolean protection_absent = headers[1]&0x01;
u_int16_t frame_length
= ((headers[3]&0x03)<<11) | (headers[4]<<3) | ((headers[5]&0xE0)>>5);
#ifdef DEBUG
u_int16_t syncword = (headers[0]<<4) | (headers[1]>>4);
fprintf(stderr, "Read frame: syncword 0x%x, protection_absent %d, frame_length %d\n", syncword, protection_absent, frame_length);
if (syncword != 0xFFF) fprintf(stderr, "WARNING: Bad syncword!\n");
#endif
unsigned numBytesToRead
= frame_length > sizeof headers ? frame_length - sizeof headers : 0;
// If there's a 'crc_check' field, skip it:
if (!protection_absent) {
fseek(fFid, 2, SEEK_CUR);
numBytesToRead = numBytesToRead > 2 ? numBytesToRead - 2 : 0;
}
// Next, read the raw frame data into the buffer provided:
if (numBytesToRead > fMaxSize) {
fNumTruncatedBytes = numBytesToRead - fMaxSize;
numBytesToRead = fMaxSize;
}
int numBytesRead = fread(fTo, 1, numBytesToRead, fFid);
if (numBytesRead < 0) numBytesRead = 0;
fFrameSize = numBytesRead;
fNumTruncatedBytes += numBytesToRead - numBytesRead;
// Set the 'presentation time':
if (fPresentationTime.tv_sec == 0 && fPresentationTime.tv_usec == 0) {
// This is the first frame, so use the current time:
gettimeofday(&fPresentationTime, NULL);
} else {
// Increment by the play time of the previous frame:
unsigned uSeconds = fPresentationTime.tv_usec + fuSecsPerFrame;
fPresentationTime.tv_sec += uSeconds/1000000;
fPresentationTime.tv_usec = uSeconds%1000000;
}
fDurationInMicroseconds = fuSecsPerFrame;
// Switch to another task, and inform the reader that he has data:
nextTask() = envir().taskScheduler().scheduleDelayedTask(0,
(TaskFunc*)FramedSource::afterGetting, this);
}
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