[asterisk-users] merge gsm files

[Mojo with Horan & Company, LLC]

Tzafrir Cohen wrote:
> On Tue, Dec 11, 2007 at 11:26:21PM +0800, Rilawich Ango wrote:
>   
>> Hi,
>>  How can I merge 2 gsm files into a single file?  I have tried to use
>> soxmix as below but failed.
>> soxmix 1.gsm 2.gsm 1-2.gsm
>>     
>
> The GNU coreutils are shipped with a special[1] tool for this task: 
>
> cat 1.gsm 2.gsm >1-2.gsm
>
> [1] Honestly, it is special. I bet the BSD cat can't do that. And I bet
> that the busybox one can't do that either.
>
>   
I thought he meant mix so they play simultaneously, not concatenate them 
together.

To clarify Tzafrir's comment a little, I think that 'cat' will only work 
for sound files if all involved are headerless.  I'm not 100% sure which 
ones are and which ones aren't headerless, but generally, this shouldn't 
work for a standard wave file.   An image showing WHY it won't work can 
be found at http://ccrma.stanford.edu/CCRMA/Courses/422/projects/WaveFormat/

Keep in mind that some files that were once headerless, like .au, can 
now be found with six 32-bit words prepended as a header, sort of a 
'new' .au format.  These would NOT be concatenatable either, unless 
those first words were stripped from the second file.  Further, the 
first file would need its third 32-bit word modified to either 
0xffffffff or the actual *new* size of the data in bytes.

Sorry, but I can't help with mixing them rather than concatenating them :)

Mojo