[asterisk-security] [asterisk-dev] downsampling slinear16 to ulaw (or alaw or g729)

[Kevin P. Fleming]

On 08/30/2010 10:16 AM, Paul Albrecht wrote:
> On Mon, 2010-08-30 at 10:02 -0500, Kevin P. Fleming wrote:
>> On 08/30/2010 09:39 AM, Paul Albrecht wrote:
>>
>>> I have a question about asterisk transcoding from wide slinear to ulaw
>>> (or alaw or g729). Specifically, the result I get when I translate from
>>> AST_FORMAT_SLINEAR16 to AST_FORMAT_ULAW is truncated, that is, I don't
>>> get a 160 samples in the output frame. Is this a bug or should I have
>>> expected the translator to truncate the result?
>>
>> How many samples were in the input frame? Is there a smoother involved?
>>
> 
> The slinear16 frame contains 320 samples and I'm getting 137 samples of
> ulaw out which is not what I expected. I was looking for a full 160
> samples of ulaw.
> 
> I don't know if a smoother was involved. Here's how I do the
> translation:
> 
> trans = ast_translate_build_path(AST_FORMAT_ULAW,AST_FORMAT_SLINEAR16);
> out = ast_translate(trans,in,0)

That certainly sounds like a bug then; there's no smoother involved with
that type of construction. Can you post the contents of the ast_frame
structure called 'in' (but not the data)?

-- 
Kevin P. Fleming
Digium, Inc. | Director of Software Technologies
445 Jan Davis Drive NW - Huntsville, AL 35806 - USA
skype: kpfleming | jabber: kfleming at digium.com
Check us out at www.digium.com & www.asterisk.org

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