Re: [Audacity-devel] Loading and working with m4p files?

[LRN <lr...@gm...>]

Bo Berglund wrote:
> On Thu, 26 Jun 2008 15:13:15 +0400, LRN<lr...@gm...>  wrote:
>
>    
>> Bo Berglund wrote:
>>      
>>> On Thu, 26 Jun 2008 11:08:29 +0400, LRN<lr...@gm...>   wrote:
>>>
>>>
>>>        
>>>>> The only thing that happened was that a *blank* dialogue titled
>>>>> "mod-script-pipe - Dialog Loaded by Plug In" was shown and then
>>>>> absolutely nothing else. No contents in the dialogue or anything else.
>>>>> Task manager shows a process "audacity.exe" as running with 11 Mb RAM
>>>>> assigned.
>>>>> I am on Windows XP Pro SP2.
>>>>>
>>>>>
>>>>>
>>>>>            
>>>> Close the dialog - Audacity window will appear after that.
>>>> If you want to get rid of it for good, remove mod-script-pipe.dll from
>>>> /modules sub-directory.
>>>>
>>>>
>>>>          
>>> Yes, I did that and Audacity appeared. :-)
>>>
>>> However the improvement now is that when I drop an M4P file into
>>> Audacity it pops up a message telling me that the M4P formatted file
>>> is a protected file and cannot be opened (or something similar).
>>> So I guess I'm out of luck here.
>>> Strangely WinAmp successfully plays the files with this extension,
>>> though...
>>>
>>>
>>>        
>> Try renaming m4p files into mp4 (changing extension).
>> If it doesn't works, could you please open Help->Debug log after
>> Audacity starts, open the M4P (or MP4) file, and drop me the log
>> contents after that?
>>
>>      
>
> I was wrong, I did not look close enough...
> There were multiple non-MP3 files and some of them were M4P while
> others were M4A and the ones I tried on WinAmp were actually the M4A
> files, which load just fine in your test version of Audacity too. :-)
>
> The M4P, though, are giving the dialogue about protection in Audacity
> and result in nothing in WinAmp.
>
> When I renamed the M4P file to MP4 and tried loading it Audacity
> worked for a while and then there was a track pair with nothing in
> them.
>    
To make long story short:
This Audacity version uses FFmpeg library to import and export audio. 
Whether it will import audio or will not - depends completely on FFmpeg.
If file extension in not in the list of supported extensions (list is 
hard-coded into Audacity and is far from being complete), Audacity 
doesn't even tries to open it. After that it complains about unsupported 
format for some specific extensions. It doesn't really means that format 
is unsupported - it only means that file extension is not in the list. 
You renamed files to MP4 (supported extension), and it worked - FFmpeg 
decided that files are readable. But for some files it didn't worked - 
as you said, it's probably the copy protection, so FFmpeg failed to 
import any data (you got empty tracks). In that case i don't see any way 
to open such files, unless you have DirectShow filter capable of 
decoding such files (if you have one, files should play allright in 
Windows Media Player).
You may look at the log (see below), but i doubt it will help.

Regarding the mess with extensions, i'll really have to do something 
with it one day. I think i'll just rig it to open *any* file with FFmpeg 
as if the file's extension is in list of supported extensions - that 
will protect the user from "misnamed" files such as M4P, M4A, M4B, MKA 
etc. FFmpeg is the last plugin in the plugin list, so that wouldn't 
harm. And, of course, plugin priority override will play it's role.

> Regarding the log I don't understand what you are referring to. In the
> Audacity application's Help menu there is no entry named "Debug".
> And in the folder where I extracted your files and from which I start
> Audacity there likewise is no Help or Debug subfolder, only a single
> "modules" subfolder...
>    
Oh, i forgot that we changed the name to "Show log".
> I believe that the Apple copy protection is at work here...
>
>    
Yes, it is.