Re: possible problems with rc6 aplay

[Mark Knecht <markknecht@attbi.com>]

Patrick,
   I'm not an Alsa expert so take all of this with a grain of salt. The
difference between 48K and 44.1K is indeed about a whole step, so that's
consistent with your results. You have 48000 samples that are supposed
to take one second to play, but you are taking more than one second to
play then. The result is the output tuning is low.

   Since CDs are ALWAYS 44.1K, this would make sense when you burn a CD.
You could get around this by resampling the 48K input down to 44.1K.
There is some open source software for doing that.

   This will change the quality of the sound a bit, and is the main
reason I always work at 44.1K.

   I don't remember how to do it, but there is an option I've seen in
some .asoundrc files that allows you to set the frequency of the
Hammerfall. I have two Hammerfalls, so I suppose I had better learn to
do that one of these days.

Good luck,
Mark


On Sun, 2002-12-15 at 13:59, patrick reardon wrote:
> hi everyone:
> 
> i'm running on a PIII with kernel 2.4.18 and Alsa 0.9.0rc6 and a Hammerfall 9636 card. 
> Alsa has been working fine for the last year, or so it seems.  recently a scsi CD burner
> was installed.  i have some recordings of live performances made with "arecord", version
> 0.9.0beta8a.  they play back just fine, but when i tried to burn them to CD, they were low
> by about 2 to 3 half steps.  
> 
> Joerg Shilling suggested that Alsa was writing the wrong headers.  so i upgraded to rc6
> and on the first try on each of the old WAV files, "aplay" also played them too slowly. 
> however, on subsequent runs, everything was fine again.  i don't understand this behaviour
> at all.
> 
> someone on LAU suggested that since it was too low by about 2-3 half steps, data was being
> recorded at 48000 but Alsa thought it was at 44100.  
> 
> info in /proc/asound/hammerfall/rme9652:
> 
> ------------snip-------------
> .
> .
> Latency: 4096 samples (2 periods of 16384 bytes)
> Hardware pointer (frames): 0
> Passthru: no
> Clock mode: autosync
> Pref. sync source: ADAT1
> 
> IEC958 input: Coaxial
> IEC958 output: Coaxial only
> IEC958 quality: Consumer
> IEC958 emphasis: off
> IEC958 Dolby: off
> IEC958 sample rate: error flag set
> 
> ADAT Sample rate: 44100Hz
> .
> .
> ---------snip-----------------
> 
> 
> for months up until about an hour ago the ADAT sample rate read 48000.  in that hour i
> changed my .asoundrc from 
> 
> 
> -----------snip---------------
> pcm.hammerfall {	#"hammerfall" is the alias for "snd-rme9652" in /etc/modules.conf
> 	type hw
> 	card0
> }
> 
> ctl.hammerfall {
> 	type hw
> 	card0
> }
> -----------snip---------------
> 
> 
> to the following
> 
> 
> -----------snip---------------
> 
> pcm.rme9652 {   #changed from "hammerfall" to "rme9652" on 12.15.2002
>    type hw
>    card 0
> }
> 
> ctl.rme9652 {   #same as above comment
>    type hw
>    card 0
> }
> ---------snip-----------------
> 
> 
> after the .asoundrc change i recorded a fresh WAV and burned it to CD but with the same
> problem -- too slow.  also, with the new .asoundrc, version rc6 plays WAV's recorded with
> the old .asoundrc and version rc6 a little too fast.  i'm at a loss for new ideas to debug
> this.
> 
> can anyone enlighten me about this, or does anyone know where i can download some
> reference WAV files (for example, a middle C tone) to check whether the burning problem
> might involve Alsa or whether it's something else in my setup?
> 
> any pointers would be greatly appreciated.
> 
> tia,
> patrick
> 
> 
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