[flac-dev] FLAC QUESTION

Rafael Velasquez rafaelvelasquez10 at gmail.com
Thu Apr 19 09:20:25 PDT 2012

Now, can someone tell me how to model the signal, for example :
*using a Fixed linear predictor for the input signal ?  <= *Sorry for the
this question, i found myself :)

2012/4/19 Rafael Velasquez <rafaelvelasquez10 at gmail.com>

> Hello, in fact :
> the sample size is bigger than the exepected size in the encoder.
> Now, can someone tell me how to model the signal, for example :
> *using a Fixed linear predictor for the input signal ? *
> 2012/4/13 Brian Willoughby <brianw at sounds.wa.com>
>> On Apr 12, 2012, at 07:12, Rafael Velasquez wrote:
>>> I'm using flac for an application.
>>> The fact is that i'm trying to encode a file that is not necessary a wav
>>> file.
>>> So, at first, i would like to know if it's possible to encode a file
>>> different from the wav file with the flac encoder ?
>> First of all, the FLAC API does not work with WAV format data - you must
>> provide raw audio samples.  If you have a WAV file, then you should use
>> other code (your own?) to extract the raw audio samples from the file,
>> leaving out the chunk headers and other, non-audio information.  You should
>> also make sure that the FLAC object is initialized to accept the same size
>> samples and channel count as you have in your data, and it would probably
>> be a good idea to match the sample rate as well for proper decoding later.
>>  Beware that the format you have may not exactly match what the FLAC
>> library wants, so you may have to alter the data slightly before sending it
>> to the API.
>> So, it doesn't matter whether you have WAV, AIFF, SDII, or some other
>> file, because your code must first extract the raw audio samples from the
>> file before calling the FLAC library.
>> Note that you can encode a WAV file as FLAC, and then later decode the
>> FLAC file as AIFF.  FLAC does not usually care what the uncompressed
>> foreign file format was (unless you use "preserve foreign metadata").
>>  These operations are supported by the command-line program, but the WAV
>> and AIFF format code is not part of the FLAC library.
>>  When i put my data into : ok = FLAC__stream_encoder_process_**interleaved(encoder,
>>> pcm, need);
>>> after some rounds in my boucl i get  :
>>> encoding: FAILED
>>> what does it really mean ? and what are the reasons to be in this case ? )
>>> I'm not english spoker, so sorry if i'm not very clear.
>> There is documentation for the FLAC API.  I do not see anything
>> describing error messages, but you could look into the source code.  My
>> guess is that "mismatch" refers to the checksum.  I do not have an answer
>> for you here, but perhaps you can continue to work on your code and find
>> the problem.
>> Brian Willoughby
>> Sound Consulting
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