ByteStreamFileSource::ByteStreamFileSource(UsageEnvironment& env, FILE* fid,
unsigned preferredFrameSize,
unsigned playTimePerFrame)
: FramedFileSource(env, fid), fFileSize(0), fPreferredFrameSize(preferredFrameSize),
fPlayTimePerFrame(playTimePerFrame), fLastPlayTime(0),
fHaveStartedReading(False), fLimitNumBytesToStream(False), fNumBytesToStream(0) {
#ifndef READ_FROM_FILES_SYNCHRONOUSLY
makeSocketNonBlocking(fileno(fFid));
#endif
// Test whether the file is seekable
fFidIsSeekable = FileIsSeekable(fFid);
}
WAVAudioFileSource::WAVAudioFileSource(UsageEnvironment& env, FILE* fid)
: AudioInputDevice(env, 0, 0, 0, 0)/* set the real parameters later */,
fFid(fid), fFidIsSeekable(False), fLastPlayTime(0), fHaveStartedReading(False), fWAVHeaderSize(0), fFileSize(0),
fScaleFactor(1), fLimitNumBytesToStream(False), fNumBytesToStream(0), fAudioFormat(WA_UNKNOWN) {
// Check the WAV file header for validity.
// Note: The following web pages contain info about the WAV format:
// http://www.ringthis.com/dev/wave_format.htm
// http://www.lightlink.com/tjweber/StripWav/Canon.html
// http://www.onicos.com/staff/iz/formats/wav.html
Boolean success = False; // until we learn otherwise
do {
// RIFF Chunk:
if (nextc != 'R' || nextc != 'I' || nextc != 'F' || nextc != 'F') break;
if (!skipBytes(fid, 4)) break;
if (nextc != 'W' || nextc != 'A' || nextc != 'V' || nextc != 'E') break;
// Skip over any chunk that's not a FORMAT ('fmt ') chunk:
u_int32_t tmp;
if (!get4Bytes(fid, tmp)) break;
while (tmp != 0x20746d66/*'fmt ', little-endian*/) {
// Skip this chunk:
u_int32_t chunkLength;
if (!get4Bytes(fid, chunkLength)) break;
if (!skipBytes(fid, chunkLength)) break;
if (!get4Bytes(fid, tmp)) break;
}
// FORMAT Chunk (the 4-byte header code has already been parsed):
unsigned formatLength;
if (!get4Bytes(fid, formatLength)) break;
unsigned short audioFormat;
if (!get2Bytes(fid, audioFormat)) break;
fAudioFormat = (unsigned char)audioFormat;
if (fAudioFormat != WA_PCM && fAudioFormat != WA_PCMA && fAudioFormat != WA_PCMU && fAudioFormat != WA_IMA_ADPCM) {
// It's a format that we don't (yet) understand
env.setResultMsg("Audio format is not one that we handle (PCM/PCMU/PCMA or IMA ADPCM)");
break;
}
unsigned short numChannels;
if (!get2Bytes(fid, numChannels)) break;
fNumChannels = (unsigned char)numChannels;
if (fNumChannels < 1 || fNumChannels > 2) { // invalid # channels
char errMsg[100];
sprintf(errMsg, "Bad # channels: %d", fNumChannels);
env.setResultMsg(errMsg);
break;
}
if (!get4Bytes(fid, fSamplingFrequency)) break;
if (fSamplingFrequency == 0) {
env.setResultMsg("Bad sampling frequency: 0");
break;
}
if (!skipBytes(fid, 6)) break; // "nAvgBytesPerSec" (4 bytes) + "nBlockAlign" (2 bytes)
unsigned short bitsPerSample;
if (!get2Bytes(fid, bitsPerSample)) break;
fBitsPerSample = (unsigned char)bitsPerSample;
if (fBitsPerSample == 0) {
env.setResultMsg("Bad bits-per-sample: 0");
break;
}
if (!skipBytes(fid, formatLength - 16)) break;
// FACT chunk (optional):
int c = nextc;
if (c == 'f') {
if (nextc != 'a' || nextc != 'c' || nextc != 't') break;
unsigned factLength;
if (!get4Bytes(fid, factLength)) break;
if (!skipBytes(fid, factLength)) break;
c = nextc;
}
// EYRE chunk (optional):
if (c == 'e') {
if (nextc != 'y' || nextc != 'r' || nextc != 'e') break;
unsigned eyreLength;
if (!get4Bytes(fid, eyreLength)) break;
if (!skipBytes(fid, eyreLength)) break;
c = nextc;
}
// DATA Chunk:
if (c != 'd' || nextc != 'a' || nextc != 't' || nextc != 'a') break;
if (!skipBytes(fid, 4)) break;
// The header is good; the remaining data are the sample bytes.
fWAVHeaderSize = (unsigned)TellFile64(fid);
success = True;
} while (0);
if (!success) {
env.setResultMsg("Bad WAV file format");
// Set "fBitsPerSample" to zero, to indicate failure:
fBitsPerSample = 0;
return;
}
fPlayTimePerSample = 1e6/(double)fSamplingFrequency;
// Although PCM is a sample-based format, we group samples into
// 'frames' for efficient delivery to clients. Set up our preferred
// frame size to be close to 20 ms, if possible, but always no greater
// than 1400 bytes (to ensure that it will fit in a single RTP packet)
unsigned maxSamplesPerFrame = (1400*8)/(fNumChannels*fBitsPerSample);
unsigned desiredSamplesPerFrame = (unsigned)(0.02*fSamplingFrequency);
unsigned samplesPerFrame = desiredSamplesPerFrame < maxSamplesPerFrame ? desiredSamplesPerFrame : maxSamplesPerFrame;
fPreferredFrameSize = (samplesPerFrame*fNumChannels*fBitsPerSample)/8;
fFidIsSeekable = FileIsSeekable(fFid);
#ifndef READ_FROM_FILES_SYNCHRONOUSLY
// Now that we've finished reading the WAV header, all future reads (of audio samples) from the file will be asynchronous:
makeSocketNonBlocking(fileno(fFid));
#endif
}
