[Speex-dev] converting unsigned short sample to signed short sample
s at pahtak.org
Wed Mar 14 00:01:56 PDT 2012
I don't understand why you're subtracting 2^15 - 1. Assuming you really do have unsigned samples (which is very odd) that have 0x8000 as the mid point of the range, then you need to subtract 0x8000, as I believe I pointed out already.
By mid point, I mean if you have a pure tone (i.e., a sine wave) that has unsigned range 0 to 0xffff, then the mid point is 0x8000. The mid point should be translated to zero.
If your samples are represented some other way, you have to tell us.
On Mar 13, 2012, at 23:28, Mashal al-shboul <shboul8989 at yahoo.com> wrote:
> Thanks a lot for replying,
> The question now is , after subtracting 32767 from each unsigned sample, will the new signed samples represent the same original voice ?
> For explanation, assume "Hi" is said in 8000 unsigned sample ,if i subtract 32767 from each sample and play the resulting 8000 sample as signed PCM samples,will they be "Hi" ?!
> Forgive me about my questions , but it's important for me and i am new to the stuff
> Best Regards,
> From: Arthurc <arthurc99 at yahoo.com>
> To: Mashal al-shboul <shboul8989 at yahoo.com>
> Sent: Wednesday, March 14, 2012 5:58 AM
> Subject: Re: [Speex-dev] converting unsigned short sample to signed short sample
> I assumed that you have unsigned input from your sound card / codec, etc.
> Actually, it is unlikely in today's hardware platform for audio application.
> If that is really the case, you can just do..
> short output = ((long) input) - 32767
> Well, maybe it is possible to do some bit manipulation to achieve the same thing.
> On 2012年3月14日, at 上午11:21, Mashal al-shboul <shboul8989 at yahoo.com> wrote:
>> Hi All,
>> I would like to get your help in my problem,
>> we know that Speex codec takes samples of type short (signed), range:-2^15 to2^15 -1 , my problem is that i have samples of type
>> unsigned short ,range: 0 to 2^16 -1. so, what should i do in order to apply speex on my unsigned samples ?.
>> There is a proposed solution to subtract 2^15-1 from each unsigned short to get it signed short, my question: is this method safe in keeping the samples meaningful for speex's processing algorithms?.
>> i hope i receive help from you. Thanks in advance
>> Speex-dev mailing list
>> Speex-dev at xiph.org
> Speex-dev mailing list
> Speex-dev at xiph.org
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