[mythtv-users] Recorded at a slightly higher pitch

[Michael T. Dean]

On 10/15/2007 02:40 PM, Rod Smith wrote:
> On Monday 15 October 2007 11:59:22 lanas wrote:
>   
>>   Has anyone noticed that recorded TV shows are replayed at a slightly
>> higher pitch, i.e. a bit faster ?  Is this a known problem ?  I was
>> listening to a TV host that was previously recorded and I can swear his
>> voice sounds higher pitched.
>>     
> Others have posted two other possible causes. I'll add this: I've seen 
> something like this once or twice in videos I've obtained from the Internet. 
> Upon investigation I found that they were recorded with an audio sampling 
> rate of 44,100 Hz. Apparently certain MythTV video tools like seeing a 48,000 
> Hz recording, and play back 44,100 Hz recordings at a higher pitch. I was 
> able to fix this problem by transcoding with mencoder and resampling the 
> audio. If this is the cause of your problem, though, you'd do better to check 
> your audio encoding options and, if possible, set them to encode at 48,000 Hz 
> rather than 44,100 Hz. I'm not positive this issue would cause this problem 
> on videos recorded within MythTV, though; as I said, I've only seen it on a 
> couple of videos I downloaded from the Internet.

More likely you have a (broken) audio configuration that prevents proper
playback of anything other than 48kHz audio.  This could occur if using
older versions of ALSA (before 1.0.9) without enabling the plug plugin
or if using newer versions of ALSA and overriding the defaults (i.e.
creating a broken .asoundrc/asound.conf).

Myth doesn't need 48kHz audio.  Sounds cards may (usually do).  Some
capture card drivers may.  Some video formats may (i.e. depending on the
audio format chosen, DVD's may require 48kHz sampling--MP-1, MP-2, DTS,
and SDDS audio must be 48kHz on DVD's).

Mike