On Thu, 27 Sep 2018 22:36:47 +0000 Peter Stuge firstname.lastname@example.org wrote:
I tried decoding, resampling and normalizing the ogg file without success so I suggest increasing amplitude at the source; move the mic closer to the speaker and use the parecord | spkmodem-recv command as documented in spkmodem-recv.c. Make sure to set your mic input volume to 0dB (and not higher!) so that you get the best possible signal, without attenuation.
On some device like the i945 Thinkpads, connecting an audio cable in the output jack plug works, so you can record a clean signal by doing that and by messing with the sound volume buttons before re-booting.
I've tried that on a gm45 Thinkpad also with coreboot, and I wasn't able to redirect the sound.