hexl-mode, while saving encoding problem

hexl-mode, while saving encoding problem

[Gelika PAPP-RAFFY]

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Hello,
 
I am editing binary files with emacs (ID3 tags in .mp3 files).
I use the hexl-mode.
When I want to save my modifications I get the question "Selet coding system" and it is asking me to choose between several like undecided-unix, mule-utf-8, etc.
 
But I don't want to encode the text, it is pure binary!
I tried to do with the "undecided" but it still modifies (and corrupts) my file.
 
Is there any possibility to overcome this problem?
 
Thanks for any help,
 
Gelika

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Re: hexl-mode, while saving encoding problem

[Peter Dyballa]

Am 08.11.2007 um 16:03 schrieb Gelika PAPP-RAFFY:

> I am editing binary files with emacs (ID3 tags in .mp3 files).
> I use the hexl-mode.
> When I want to save my modifications I get the question "Selet  
> coding system" and it is asking me to choose between several like  
> undecided-unix, mule-utf-8, etc.

There is a variable, file-coding-system-alist, that also lists file  
name extensions for which no-conversion is applied upon reading or  
writing. Obviously no-one has edited an MP3 file before, so this is  
not mentioned there.

It might be worth to write a bug report and ask for this enhancement.

To solve your problem now you can add to your init file this code:

	(add-to-list 'file-coding-system-alist '("\\.mp3\\'" . no-conversion))

To have it set at once put the line into the *scratch* buffer,  
position the cursor at its end and press C-j. Then open, edit, and  
save the MP3 file again.

--
Greetings

   Pete

"Isn't vi that text editor with two modes... one that beeps and one
that corrupts your file?" -- Dan Jacobson, on comp.os.linux.advocacy

Re: hexl-mode, while saving encoding problem

[martin rudalics]

 > I am editing binary files with emacs (ID3 tags in .mp3 files).

Is there a special mode for editing ID3 tags?

 > I use the hexl-mode.
 > When I want to save my modifications I get the question "Selet coding system"
 > and it is asking me to choose between several like undecided-unix, mule-utf-8, etc.

Does it work when you use `find-file-literally' to open the file?

Re: hexl-mode, while saving encoding problem

[Stefan Monnier]

> I am editing binary files with emacs (ID3 tags in .mp3 files).
> I use the hexl-mode.
> When I want to save my modifications I get the question "Selet coding system" and it is asking me to choose between several like undecided-unix, mule-utf-8, etc.
 
Sounds like a bug.  Please report it with M-x report-emacs-bug.
Don't forget to include a recipe to reproduce it starting from "emacs -Q".


        Stefan

RE: hexl-mode, while saving encoding problem

[Gelika PAPP-RAFFY]

Thanks for your tip, it works fine.

Now I have a very basic problem: My emacs installation is on a virtual
machine with no internet access, so that I can not report the bug from emacs
directly.
If this is to be corrected as a bug, then there should be also other
compressed audio files added to this list (I didn't try to edit them so I am
not sure they would save wrongly): .wma, .aac, .m4a and probably also ogg
vorbis files, I don't know the extensions.

Thank you for the prompt support, I had been searching the net for quite a
while now *what* could be corrupting and how not to corrupt my files :-))))

Gelika

> -----Original Message-----
> From: Peter_Dyballa@Web.DE [mailto:Peter_Dyballa@Web.DE] 
> Sent: Thursday, November 08, 2007 4:40 PM
> To: Gelika PAPP-RAFFY
> Cc: help-gnu-emacs@gnu.org
> Subject: Re: hexl-mode, while saving encoding problem
> 
> 
> Am 08.11.2007 um 16:03 schrieb Gelika PAPP-RAFFY:
> 
> > I am editing binary files with emacs (ID3 tags in .mp3 files).
> > I use the hexl-mode.
> > When I want to save my modifications I get the question "Selet  
> > coding system" and it is asking me to choose between several like  
> > undecided-unix, mule-utf-8, etc.
> 
> There is a variable, file-coding-system-alist, that also lists file  
> name extensions for which no-conversion is applied upon reading or  
> writing. Obviously no-one has edited an MP3 file before, so this is  
> not mentioned there.
> 
> It might be worth to write a bug report and ask for this enhancement.
> 
> To solve your problem now you can add to your init file this code:
> 
> 	(add-to-list 'file-coding-system-alist '("\\.mp3\\'" . 
> no-conversion))
> 
> To have it set at once put the line into the *scratch* buffer,  
> position the cursor at its end and press C-j. Then open, edit, and  
> save the MP3 file again.
> 
> --
> Greetings
> 
>    Pete
> 
> "Isn't vi that text editor with two modes... one that beeps and one
> that corrupts your file?" -- Dan Jacobson, on comp.os.linux.advocacy
> 
> 

Re: hexl-mode, while saving encoding problem

[Peter Dyballa]

Am 09.11.2007 um 09:36 schrieb Gelika PAPP-RAFFY:

> Now I have a very basic problem: My emacs installation is on a virtual
> machine with no internet access, so that I can not report the bug  
> from emacs
> directly.

That does not matter! Just select the 'Send Bug Report...' entry from  
the Help menu and copy the contents of the newly created *mail*  
buffer into your eMail client's compose window. Do the same with  
address and subject. Then complete the message's body.

> If this is to be corrected as a bug, then there should be also other
> compressed audio files added to this list (I didn't try to edit  
> them so I am
> not sure they would save wrongly): .wma, .aac, .m4a and probably  
> also ogg
> vorbis files, I don't know the extensions.

There is also FLAC (.flac) and SHTN (.shn) and there are many video  
and graphics formats. Ogg Vorbis uses .ogg, at least in those  
downloaded live concerts I have.

When filling out the bug report please concentrate on the failure of  
hexl-mode, as Stefan Monnier emphasised. IMO too this should not have  
happened, since no-one would edit a simple text file with an encoding  
as a binary in hexl-mode. So there seems to be some bug when you're  
asked to give some text encoding's name. Mentioning of file-coding- 
system-alist should not be the bug report's main concern, merely a  
remark describing how you solved your problem, since its purpose  
might be aiming towards text files.

--
Greetings

   Pete

"Let's face it; we don't want a free market economy either."
         James Farley, president, Coca-Cola Export Corp., 1959

Re: hexl-mode, while saving encoding problem

[Mark Hood]

I often have to edit binary files of various types and run into the
same problem.  The following works for me in those situations:

(setq default-enable-multibyte-characters nil)