[erlang-questions] ANN: wave.erl

Ivan Uemlianin <>
Tue Jun 1 12:16:03 CEST 2010


Cool!

I intend to write a small collection of scripts for audio (esp. speech) 
processing (reading and writing the files was an obvious first step).  
On my todo list is to set up a repos on github.

Best

Ivan


On 01/06/2010 10:36, Mazen Harake wrote:
> Tip: It is Open Source... Submit a patch ;)
>
> /Mazen
>
> On 01/06/2010 10:19, Kostis Sagonas wrote:
>> Ivan Uemlianin wrote:
>>> Dear All
>>>
>>> Please find below wave.erl, an erlang script for reading and writing 
>>> .wav audio files.  I am releasing it under the ISC license.
>>>
>>> The script exports functions read/1, write/3 and write/2, and the 
>>> wave record:
>>>
>>>     -record(wave, {audio_format, sample_rate, data}).
>>>
>>> where:
>>> - audio_format is an unsigned integer (currently only 1, i.e. pcm 
>>> encoding, is supported);
>>> - sample_rate is an unsigned integer (i.e., samples per second, in 
>>> kHz);
>>> - data is a list of lists of signed integers, one list for each 
>>> channel (e.g., stereo will have two lists of integers).
>>>
>>> read(FileName) reads a wav file and returns a wave record.
>>>
>>> write(WavRecord, FileName, BitsPerSample) writes the wave record 
>>> WavRecord to the file FileName with the sample size BitsPerSample.
>>>
>>> write(WavRecord, FileName) just calls write/3 with BitsPerSample = 16.
>>
>> Rather than writing all the above, which is just words in a mail, why 
>> don't you add the following to the file which is machine-checkable 
>> documentation which is now part of the code?
>>
>> ------------------------------------------------------------------------- 
>>
>> -type audio_format() :: 1. % non_neg_integer() see wav docs for formats
>> -type sample_rate()  :: non_neg_integer().
>> -record(wave, {audio_format :: audio_format(),
>>                sample_rate  :: sample_rate(),
>>                data         :: [[integer()]]}).
>> -type wave() :: #wave{}.
>>
>> -spec read(file:filename()) -> wave().
>>
>> ...  AND FURTHER DOWN
>>
>> -spec write(wave(), F) -> {'ok', F} when is_subtype(F, file:filename()).
>>
>> -spec write(wave(), F, sample_rate()) -> {'ok', F} when is_subtype(F, 
>> file:filename()).
>> -------------------------------------------------------------------------- 
>>
>>
>> [although I do not see any compelling reason for the write functions 
>> to return {'ok', F} rather than just 'ok' at the moment.]
>>
>> Kostis
>>
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-- 
============================================================
Ivan A. Uemlianin
Speech Technology Research and Development

                     
                      www.llaisdy.com
                          llaisdy.wordpress.com
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     "Froh, froh! Wie seine Sonnen, seine Sonnen fliegen"
                      (Schiller, Beethoven)
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