On Fri, 2003-08-15 at 22:56, Eben King wrote:
> I'm far from an expert but...
>
> If they're like MP3s, then the only way that I know of to combine them is
> to do something like:
>
> { decode $first_file ; decode $second_file ; } | encode > $combined_file
>
> but that involves another decode-encode cycle, which is a Bad Thing.
I think a benchmark is in order...
My machine is an AthlonXP 1600+ with 256 megs of ram. Assume I want to
combine Holst's Mars, the Bringer of War with Weird Al Yankovic's My
Bologna. This sums to about 9 1/2 minutes of audio.
Method A:
time ogg123 -d raw -f - 01\ Mars\,_the_bringer_of_war.ogg
../Weird_Al_Yankovic/My_Bologna.07.ogg.ogg | oggenc -q3 -r - >
/tmp/MarsBologna.ogg
(encoding/decoding output)
real 1m45.706s
user 1m25.329s
sys 0m3.423s
File size: 7.1 megabytes
Method B:
time cat 01\ Mars\,_the_bringer_of_war.ogg
../Weird_Al_Yankovic/My_Bologna.07.ogg.ogg >
/tmp/MarsBolognaB.ogg
real 0m0.167s
user 0m0.004s
sys 0m0.100s
File size: 11 megabytes
As you can see, the second approach is about 632.97 times faster. The
resulting file is larger because I encode my ripped CDs at quality 5
instead of 3 [ripped with the excellent abcde]. The 'cat' approach also
doesn't degrade the quality of the output. Only you can decide which
way fits your needs!
- Daniel Holth
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