[Mplayer-users] mp3 downsampling/mixing? (again)

Arpi arpi at thot.banki.hu
Tue Aug 14 23:20:15 CEST 2001


> A while ago, I asked about a feature of
> 1) changing samplingrate of MP3 streams (e.g from 44100 to 22050 kHz, only
> supported and easy ratios, like 1/2 or so) at play
> 2) downmixing to mono (or playing only single channel in joint-stereo)
> both ways work e.g. with mpg123 to speed up mp3 output (no, that's _NOT_
> only 2% on my machine)
> It might be possible with a registry entry in DLL, or by not too much work
> in mp3-library.
> But somehow that idea fell asleep. If this is possible, can somebody
> comment on this?

yes, i did it... 
in mp3lib/sr1.c change:
    fr.down_sample=0; //2;
to value of 1 (1:2) or 2 (1:4) downsampling of freq.

for getting mono output, change the last parameter of MP3_Decode()
in dec_audio.c from -1 to 1 (left only) or 2(right only) or 3 (mixed)

but i got only a few percent of speedup... 

A'rpi / Astral & ESP-team

mailto:arpi at thot.banki.hu

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