[mythtv-users] Correcting high-pitched ("Chipmunks") audio

Nick Morrott knowledgejunkie at gmail.com
Mon Aug 4 13:11:50 UTC 2008

On 04/08/2008, Rod Smith <mythtv at rodsbooks.com> wrote:
> Hi,
>  There's a problem that's been annoying me with some video files obtained on
>  the Internet lately: Some (but by no means all) of these files have audio
>  that's too high-pitched, resulting in "Chipmunks" voices. The audio is in
>  sync with the picture, but peoples' voices are just off. For some characters
>  (particularly men with deep voices), this is quite distracting. This occurs
>  when playing under MythTV's built-in player, mplayer, xine, and every other
>  player I've tried (including QuickTime under Mac OS X). Here are some of the
>  potentially relevant lines from midentify:
>  ID_VIDEO_FPS=23.976
>  ID_VIDEO_CODEC=ffodivx
>  ID_AUDIO_RATE=48000

Assuming the files really do have good audio - are there /any/ systems
that play the file(s) normally? Have you tried Media Player Classic on
Windows for example, with a suitable AC3 codec installed?

The audio is listed as being a52 (Dolby Digital) which could cause
playback problems if you are running your audio at something other
than 48kHz and the audio is being rate-converted on-the-fly. Do you
have digital audio passthrough configured in mythfrontend setup? Does
extra verbose logging in mythfrontend show any useful audio messages?

It /could/ point to an ALSA sampling rate configuration issue as all
media players exhibit the same behaviour (not sure about MacOS

i) are you using an ALSA configuration file?
ii) how are you connecting your audio output to your TV/speakers/receiver?
iii) do you have any other audio issues (ripped CDs play too fast/will
not play etc)?
iv) have tried extracting the audio and playing that directly?

Nick Morrott

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