Stuttering/Choppiness in MythMusic

[Ken Emerson <kenneth.emerson@…>]

When playing mp3 files via MythMusic and using "default" for the music audio output device, the sound stutters. The device used for hardware audio device is a Creative Labs Sound Blaster Live! 24 bit USB device using S/PDIF digital output to the amplifier. The device setup in the MythTV general settings for the audio output device is: ALSA:iec958:CARD=EXTERNAL,DEV=0. When watching recordings, the sound is perfect. Using the OSS device for the music audio output device (/dev/dsp1) also works perfectly. Disabling the upmixing in the music general settings makes the music playback better, but the stuttering is still very much evident. I have attached the sections from the frontend log that shows the audio setup for both watching recordings and for listening to music. Other than the sampling rate being different, there must be something else done differently in setting up the audio between watching recordings and listening to music that perhaps only effects the usb_snd driver.

Pulseaudio is disabled on this system. OS: Ubuntu desktop 10.04

Please attach all output as a file in bug reports. MythTV Version : 26336 MythTV Branch : trunk Network Protocol : 62 Library API : 0.23.20100913-1 QT Version : 4.6.2 Options compiled in:

linux debug using_alsa using_oss using_pulse using_pulseoutput using_backend using_bindings_perl using_bindings_python using_directfb using_dvb using_firewire using_frontend using_hdhomerun using_hdpvr using_iptv using_ivtv using_joystick_menu using_libfftw3 using_lirc using_mheg using_opengl_video using_opengl_vsync using_qtdbus using_qtwebkit using_v4l using_x11 using_xrandr using_xv using_xvmc using_xvmc_vld using_xvmcw using_bindings_perl using_bindings_python using_mythtranscode using_opengl using_vdpau using_ffmpeg_threads using_live using_mheg

[Ken Emerson <kenneth.emerson@…>]

Excerpts from frontend log (-v audio,playback)

[Ken Emerson <kenneth.emerson@…>]

ALSA user system information

[Kenni Lund [kenni a kelu dot dk]]

jyavenard, I'm assigning this one to you, feel free to reassign if I'm wrong.

[Ken Emerson <kenneth.emerson@…>]

Recording illustrating stuttering (using "default")

[Ken Emerson <kenneth.emerson@…>]

Same song using OSS (/dev/dsp1)

[Ken Emerson <kenneth.emerson@…>]

I have attached two short recordings (using my phone as a recorder -- sorry about the quality) that illustrate the difference between using alsa and oss for playing music.

[qeldroma@…]

I have the same using mythmusic for mp3 playback since i "upgraded" from v0.23.1 to the trunk. Disabling "5.1 upmixing" made it better, but still hearable.

Perhaps something about 44.1kHz vs. 48kHz? Don't know, if an error in sampling would sound like that...?

[JYA]

Creative labs card are known to not work properly with anything but 48kHz through spdif.

Using 0.24, check the Advanced Settings -> Force resample to 48kHz and see if it makes things any better

[Ken Emerson <kenneth.emerson@…>]

Thank you for the research and suggestion. Resampling to 48kHz got rid of the stuttering. All is well now using alsa for both video and music.

[JYA]

issue turned out to be audio card..