Reading in Wav file

[Ap0C552]

I am trying to write code to read and write wavfiles.

My code only accepts 16bit uncompressed PCM wav files atm.

I am running my test of my code with a wavfile that is 43,847,784 bytes in size. So minus 44 byte header, that should be 43,847,740.

But when I print out SubChunk2Size, that I have read in from the header, it prints a value of 27070524.

I have no explanation for this discrepancy. All other values seem to be reading in properly.

my code to read the WavFile

Code: Select all

WavFile::WavFile(std::string filename)
{
	std::ifstream ifs;		
	ifs.open( filename, std::ios::binary | std::ios::in );

	LogStream(LOG_DEBUG) << "WavFile::WavFile - - - - BEGIN READING WAV - - - -";

	if(ifs.fail())
		throw std::invalid_argument("WavFile::WavFile : Failed to open wavFile "+filename);
		
	char hbytes[HEADER_SIZE];

	ifs.read(hbytes , HEADER_SIZE);

	// check that this is actually a wave file
    bool valid_riff = hbytes[0]=='R' && hbytes[1]=='I' && hbytes[2]=='F' && hbytes[3]=='F';
    bool valid_wave = hbytes[8]=='W' && hbytes[9]=='A' && hbytes[10]=='V' && hbytes[11]=='E';
	bool valid_ftm = (hbytes[12]=='f' && hbytes[13]=='m' && hbytes[14]=='t' && hbytes[15]==' ');
	bool valid_data = (hbytes[36]=='d' && hbytes[37]=='a' && hbytes[38]=='t' && hbytes[39]=='a');

	LogStream(LOG_DEBUG) << "WavFile::WavFile - valid_riff="<<valid_riff<<" valid_wave="<<valid_wave<<" valid_ftm="<<valid_ftm<<" valid_data="<<valid_data;
	if(!(valid_data && valid_ftm && valid_riff))
		throw std::invalid_argument("WavFile::WavFile : Invalid argument - unable to open wavfile "+filename);

	int audioFormat = ReadShort(hbytes , 20);
	int SubChunk1Size = ReadInt(hbytes , 16);

	if(audioFormat != 1 || SubChunk1Size != 16)
		throw std::invalid_argument("WavFile::WavFile : Only uncompressed PCM wave format supported."+filename);	

	int subChunk2size = ReadInt(hbytes , 40);
	m_header.num_channels = ReadShort(hbytes , 22);
	m_header.sample_rate = ReadInt(hbytes , 24);
	m_header.bits_per_sample = ReadShort(hbytes , 34);

	LogStream(LOG_DEBUG) << "WavFile::WavFile num_channels="<<m_header.num_channels << " sample_rate="<<m_header.sample_rate<<" bits_per_sample="<<m_header.bits_per_sample;

	m_pcm_data.resize( subChunk2size / sizeof(int16_t) );

	LogStream(LOG_DEBUG) << "WavFile::WavFile - subChunk2size = "<<subChunk2size;
	LogStream(LOG_DEBUG) << "WavFile::WavFile - m_pcm_data.size() = "<<m_pcm_data.size();
	ifs.read((char*)m_pcm_data.data() , subChunk2size);

	LogStream(LOG_DEBUG) << "WavFile: ifstream failbit="<<ifs.fail()<<" badbit="<<ifs.bad()<<" goodbit="<<ifs.good();

	ifs.close();

	LogStream(LOG_DEBUG) << "WavFile::WavFile - - - - END READING WAV - - - -\n";
	LogStream(LOG_DEBUG) << "WavFile::WavFile";
} 

And the output in the log...

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[2572] [SLOG][D] - WavFile::WavFile - - - - BEGIN READING WAV - - - -
[2572] [SLOG][D] - WavFile::WavFile - valid_riff=1 valid_wave=1 valid_ftm=1 valid_data=1
[2572] [SLOG][D] - WavFile::WavFile num_channels=2 sample_rate=96000 bits_per_sample=16
[2572] [SLOG][D] - WavFile::WavFile - subChunk2size = 27070524
[2572] [SLOG][D] - WavFile::WavFile - m_pcm_data.size() = 13535262
[2572] [SLOG][D] - WavFile: ifstream failbit=0 badbit=0 goodbit=1
[2572] [SLOG][D] - WavFile::WavFile - - - - END READING WAV - - - -

[Miles1981]

Did you check that you don't have different kind of chunks before your data?

[Ap0C552]

Did you check that you don't have different kind of chunks before your data?

I am not sure what you mean? I read in the header and parsed it data, and it is congruent with what I assumed. Other than that, I am not sure what you mean.

[BertKoor]

I am trying to write code to read and write wavfiles.

Snakepit alert !!!
http://www.kvraudio.com/forum/viewtopic ... 3&t=447027
It's far easier to just reuse a library that already does that than reinvent this wheel again.

[Ap0C552]

My solution to this problem was to read in the header into an unsigned char array, instead of a signed char array.

It's far easier to just reuse a library that already does that than reinvent this wheel again.

I did initially look for this. If there were a single .h file I could use, that would be great. But I don't want to import some library like port audio or something.

Suggestions?

[adammonroe]

I think it's good practice to write your own wav parser because inevitably you'll end up writing a midi reader and other audio-related stuff. You'll probably end up writing code around and on top of it, and you'll need to customize the code from time to time, so I think it's more elegant if you write it from the ground up, rather than using some prefab code.

Glad you solved your issue. I wrote my own wav-reader class a long time ago and i use it in nearly every plugin I make.