Audacity Forum

Audacity 2.1.3
Ubuntu 16.04 amd64

This also affects windows version.

Importing 16bit signed raw results strange waveform, seems like non linear a-law or u-law. Also most of the raw formats imports result unexpectedly. attachments:
sin.raw: a signed 16-bit big-endian linear sine wave

unable to upload raw file, using this xxd dump instead

Note that Audacity attempts to guess the raw data format, but it's no more than an educated guess. It is not possible to make this guess 100% accurate, which is why audio files usually contain header information.

Please test importing this file as RAW data (you can change the file extension if you wish - I've just named it as a WAV file so that I can upload it to the forum). The settings should be like this (these are automatically selected on my Xubuntu 16.04 machine): And this is the (correct) waveform as it appears on my machine after importing as RAW:

terrance_h wrote:Importing 16bit signed raw results strange waveform

Not surprising, because "sin.txt" is not 16-bit signed PCM.
Where did that file come from?

Here's the first 100 bytes as signed 16-bit big endian:
(it does not look like a sine wave to me)

steve wrote:

terrance_h wrote:Importing 16bit signed raw results strange waveform

Not surprising, because "sin.txt" is not 16-bit signed PCM.
Where did that file come from?

i cannot upload the raw, the txt is its xxd dump

you can "xxd -r " to restore the raw.

the correct waveform is like this (using matplotlib)

steve wrote:Note that Audacity attempts to guess the raw data format, but it's no more than an educated guess. It is not possible to make this guess 100% accurate, which is why audio files usually contain header information.

Please test importing this file as RAW data (you can change the file extension if you wish - I've just named it as a WAV file so that I can upload it to the forum).

16-bit_RawDataTest.wav

The settings should be like this (these are automatically selected on my Xubuntu 16.04 machine):

fullwindow-Import Raw Data-000.png

And this is the (correct) waveform as it appears on my machine after importing as RAW:

firsttrack000.png

Thanks! That explains it.

But this is exactly the issue. we need the "Import RAW Data" for raw files have no valid headers. or we can just "open" them.

steve wrote:Note that Audacity attempts to guess the raw data format, but it's no more than an educated guess. It is not possible to make this guess 100% accurate, which is why audio files usually contain header information.

Please test importing this file as RAW data (you can change the file extension if you wish - I've just named it as a WAV file so that I can upload it to the forum).

The attachment 16-bit_RawDataTest.wav is no longer available

The settings should be like this (these are automatically selected on my Xubuntu 16.04 machine):

The attachment fullwindow-Import Raw Data-000.png is no longer available

And this is the (correct) waveform as it appears on my machine after importing as RAW:

The attachment firsttrack000.png is no longer available

the attachment is my RAW, extracted from an oscilloscope.

Sometimes I use audacity as a scientific tool, viewing and processing waveform.

terrance_h wrote:sin.raw.notrealwav.wav

On my machine, that is detected by Audacity as signed 8-bit, little endian, 2 channel (stereo), which produces this waveform: