Save without file type

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Save without file type

Permanent link to this post Posted by hellocatfood » Mon Nov 02, 2009 6:42 pm

I've imported some raw data into audacity (1.3.9) and I want to save the changes back to the file but I can't see how to without using the export dialogue and when I use the export dialogue I'm limited by the options it gives me.

To see what I mean try importing raw data into mhwavedit (available in the ubuntu repositories)

Thanks for your help!
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Re: Save without file type

Permanent link to this post Posted by steve » Mon Nov 02, 2009 6:46 pm

To Export as RAW, select "Other uncompressed file types" in the Export dialogue, then click on the Options button.
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Re: Save without file type

Permanent link to this post Posted by hellocatfood » Mon Nov 02, 2009 6:53 pm

stevethefiddle wrote:To Export as RAW, select "Other uncompressed file types" in the Export dialogue, then click on the Options button.


That exports it as a .raw file, which I don't want. As an example, if I imported raw data from a .bmp image I'd want to write that data back to that file. mhwavedit can do it by saving as "raw pcm data"
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Re: Save without file type

Permanent link to this post Posted by steve » Mon Nov 02, 2009 7:42 pm

hellocatfood wrote:mhwavedit can do it by saving as "raw pcm data"

See the "Encoding" options in the Options pop-up and select whichever type of RAW PCM data you require.
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Re: Save without file type

Permanent link to this post Posted by hellocatfood » Mon Nov 02, 2009 7:54 pm

stevethefiddle wrote:See the "Encoding" options in the Options pop-up and select whichever type of RAW PCM data you require.


Thanks for the advice but it didn't work. Do you know the exact settings to use to save the raw imported data back to the original.bmp file? I've tried several different methods including matching the export settings to the import settings and still nothing.
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Re: Save without file type

Permanent link to this post Posted by steve » Mon Nov 02, 2009 11:56 pm

I'm not quite sure what you are trying to do, but I'm guessing that you are hoping to Import an image file into Audacity, mess around with it, and Export it back out as an image.

RAW PCM files are "headerless" (just the actual data), but .bmp files are not just raw data. Typically a .bmp file will have the bmp header, followed by a DIB header, followed by the colour palette, and only then the actual data. So you can't just Export RAW data and expect it work as a .bmp file even if you get the data format correct.

If you are using a graphic program that can handle raw data (as supplied by some digital cameras) then you still have problems as even RAW image files will typically have a header, but to make the situation considerably worse there is no accepted standard for a RAW image format - there's almost as many RAW image formats as there are different models of digital cameras.

As you have seen by the Export options in Audacity, there are also many kinds of RAW data for audio files.

I'm no expert on this, and I'd be interested to know of any do-it-yourself way of getting round these problems.

You have mentioned "Mhwavedit" - have you been using this program? Have you had any success with exporting data from it and producing a readable image file, or is this just at the "idea" stage?
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Re: Save without file type

Permanent link to this post Posted by hellocatfood » Tue Nov 03, 2009 12:19 am

stevethefiddle wrote:I'm not quite sure what you are trying to do, but I'm guessing that you are hoping to Import an image file into Audacity, mess around with it, and Export it back out as an image.

I'm doing something called databending, which involves loading an image or film in a binary data editor or audio editor, messing around with it and then saving the data back to the image.

You have mentioned "Mhwavedit" - have you been using this program? Have you had any success with exporting data from it and producing a readable image file, or is this just at the "idea" stage?

I've actually used this program successfully. The reason that I don't just use that instead is that Audacity has more features and is a lot easier to use than mhwavedit. The way that I write data in that program is as follows
*Load the data
*Add some effects, being sure not to edit the first few seconds, which is usually the heder
*Press save
*It'll ask me what to save it as and I choose Raw PCM data.

The difference I see between how each program saves data is that mhwavedit saves the data back to the file. Unless it's a feature that I've missed, in Audacity when you want to save any changes back to your original file you have to export and overwrite the original file, there doesn't seem to be a way to just save the changes made to the file back to the file. mhwavedit saves the data back to the file, allowing me to successfully edit an image in an audio editing program

Some people have had success in loading the .raw output from the method you described but that is using photoshop to import the files. As I'm on Ubuntu (and have no desire to load a copy via wine) this isn't really an option to me.

So, is there a way to simply save the changes back to the original file without having to overwrite the whole file?
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Re: Save without file type

Permanent link to this post Posted by steve » Tue Nov 03, 2009 2:43 am

Oh OK - I wasn't a million miles off.
Try Importing and Exporting as either U-Law or A-Law
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Re: Save without file type

Permanent link to this post Posted by hellocatfood » Tue Nov 03, 2009 9:44 am

You deserve a medal! After importing/exporting as U or A-Law and changing the file extension back to .bmp the original picture was restored. Of course, I did a bit of manipulation first and this is what I got:

Image

Thanks again!
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Re: Save without file type

Permanent link to this post Posted by steve » Tue Nov 03, 2009 10:59 am

Cool / Weird :D
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