Raw import of 16-bit PCM, 8KHz has problem

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elmerbug
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Raw import of 16-bit PCM, 8KHz has problem

Post by elmerbug » Wed Jan 30, 2008 3:42 pm

Folks, I am a newbie. I have a problem when I import raw PCM files (16 bit, 8KHz sampling, Motorola PCM). They import fine, but sound bad. Imported into Cool Edit, they are fine. Am I missing something? I attached a sample.
Thanks for your guidance.

Locopomo
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Re: Raw import of 16-bit PCM, 8KHz has problem

Post by Locopomo » Thu Jan 31, 2008 10:33 pm

There's no attached file - could you repost?

elmerbug
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Re: Raw import of 16-bit PCM, 8KHz has problem

Post by elmerbug » Thu Jan 31, 2008 11:41 pm

Sorry, I did not notice that the size limit is 256KB. I will re-upload.
Thanks,
Don

elmerbug
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Re: Raw import of 16-bit PCM, 8KHz has problem

Post by elmerbug » Fri Feb 01, 2008 12:07 am

Ok, I have been trying to upload the sample, and every attempt is rejected with something like "The extension pcm is not allowed". Don

alatham
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Re: Raw import of 16-bit PCM, 8KHz has problem

Post by alatham » Fri Feb 01, 2008 6:28 pm

Yes, we have a fascist dictator problem with file uploads (I'm looking at you, Buanzo ;)). If you put the file in a .zip archive, it will work.

I suspect that you've got the endianness of the file wrong, or something like that.

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Re: Raw import of 16-bit PCM, 8KHz has problem

Post by elmerbug » Sat Feb 02, 2008 12:49 am

Whew! Thanks. Here goes.
Attachments
test2_tx.zip
(69.24 KiB) Downloaded 275 times

Locopomo
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Re: Raw import of 16-bit PCM, 8KHz has problem

Post by Locopomo » Sat Feb 02, 2008 10:51 pm

I got it working, but it took a bit of messing about with settings. Various permutations resulted in a badly distorted, unintelligible track until this course of action got some results.....

Import - Raw Data - Signed 8 bit PCM - 2 Channels (Stereo) - Default Endianness -
Start Offset 0 Bytes - Amount to Import 100% - Sample Rate 8000 Hz

This opened the file, but one channel was badly distorted. So....

Track Menu (Down arrow to the right of track name) - Split Stereo track
Close distorted channel (X to left of track name)
On the remaining track, Track Menu - Mono

There, a clear recording of a telephone call. I can't explain why it takes all the messing around (or why Cool Edit seems to do it instinctively), but it is a fix of sorts. Maybe someone can come up with an explanation or indeed a quicker solution.

elmerbug
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Re: Raw import of 16-bit PCM, 8KHz has problem

Post by elmerbug » Mon Feb 04, 2008 9:05 pm

Folks,
Thanks for the input. as alatham suggested, it is an endianess issue. Motorola PCM files are big endianess files. So, importing as 16-bit, big-endianess, mono works like a charm.

Don

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