[Flac-dev] Storing FLAC in Matroska

[Jory]

First, Thank you for your answers.

I using the following code to try simply decode a flac file and write the
decoded data raw PCM file. The resulting file is just noise and pops, so is
the decoded data in a different format than PCM?

struct flacData {
 FILE *inputFile;
 FILE *outputFile;
 char *filename;
};

FLAC__StreamDecoderReadStatus flac_DecoderReadCallback(const
FLAC__StreamDecoder *decoder, FLAC__byte buffer[], unsigned *bytes, void
*client_data)
{
 flacData *ourData = (flacData *)client_data;

 *bytes = fread((void *)buffer, 1, *bytes, ourData->inputFile);

 return FLAC__STREAM_DECODER_READ_STATUS_CONTINUE;
};

FLAC__StreamDecoderWriteStatus flac_DecoderWriteCallback(const
FLAC__StreamDecoder *decoder, const FLAC__Frame *frame, const FLAC__int32
*const buffer[], void *client_data)
{
 flacData *ourData = (flacData *)client_data;

 for(int current_sample = 0; current_sample < frame->header.blocksize;
current_sample++)
 {
  for(int channel = 0; channel < frame->header.channels; channel++)
  {
   fwrite((void *)&buffer[channel][current_sample], 1, 1,
ourData->outputFile);
  }
 }

 return FLAC__STREAM_DECODER_WRITE_STATUS_CONTINUE;
};

void flac_DecoderMetaDataCallback(const FLAC__StreamDecoder *decoder, const
FLAC__StreamMetadata *metadata, void *client_data)
{
 flacData *ourData = (flacData *)client_data;

};

void flac_DecoderErrorCallback(const FLAC__StreamDecoder *decoder,
FLAC__StreamDecoderErrorStatus status, void *client_data)
{
 flacData *ourData = (flacData *)client_data;

};

int main(int argc, char* argv[])
{
 //Create the FLAC stream decoder
 FLAC__StreamDecoder *flac_file = FLAC__stream_decoder_new();

 //Setup the callbacks
 FLAC__stream_decoder_set_read_callback(flac_file,
(FLAC__StreamDecoderReadCallback)flac_DecoderReadCallback);
 FLAC__stream_decoder_set_write_callback(flac_file,
(FLAC__StreamDecoderWriteCallback)flac_DecoderWriteCallback);
 FLAC__stream_decoder_set_metadata_callback(flac_file,
(FLAC__StreamDecoderMetadataCallback)flac_DecoderMetaDataCallback);
 FLAC__stream_decoder_set_error_callback(flac_file,
(FLAC__StreamDecoderErrorCallback)flac_DecoderErrorCallback);

 //Set our data up
 flacData *flacObjData = new flacData;
 flacObjData->filename = "C:\\My Music\\44.1Hz Stereo PCM_5.flac";
 flacObjData->inputFile = fopen(flacObjData->filename, "rb");
 flacObjData->outputFile = fopen("test.raw", "wb");
 FLAC__stream_decoder_set_client_data(flac_file, (void *)flacObjData);

 //Init the decoder
 FLAC__stream_decoder_init(flac_file);
 //Start decoding, the callbacks do all the work from here
 FLAC__stream_decoder_process_until_end_of_stream(flac_file);
 return 0;
}

----- Original Message -----
From: "Josh Coalson" <xflac at yahoo.com>
To: "Jory" <jcsston at ToughGuy.net>; <flac-dev at lists.sourceforge.net>
Cc: <Matroska-devel at lists.matroska.org>
Sent: Tuesday, July 08, 2003 5:02 PM
Subject: Re: [Flac-dev] Storing FLAC in Matroska


> --- Jory <jcsston at ToughGuy.net> wrote:
> > Hello,
> >     I'm looking into storing FLAC audio in Matroska and I have a few
> > questions.
> >
> > 1. Can I use libflac to extract the compressed frames?
> > Or will I need to write up a simple file parser?
>
> I'm not sure I understand your question, but one unfortunate
> fact about native FLAC is that you cannot discover the frame
> boundaries without decoding.  But you can decode a file, and
> after each frame get the current stream position from the
> decoder, which will tell you where to chop the original stream.
> See the source for metaflac for an example, where it uses this
> method to add seekpoints to a seektable.
>
> > 2. What is required to decode the frames?
> > From the docs I understand that you need the FRAME and you may need
> > the
> > METADATA_BLOCK.
>
> If it is in the streamable subset, you need only what's in the
> frames.  If not, you may need some numbers from the STREAMINFO
> metadata block.  Search for 'subset' on
> http://flac.sourceforge.net/format.html
>
> Josh
>
>
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