How can one determine whether an Intel HDA sound card supports playing back the input sound in real time? This feature is sometimes called microphone feedback, echo or play-through. I want to enable mic feedback in order to hear my digital piano while recording it with Audacity. The piano is connected to my computer with a jack-jack audio cable (it also has a MIDI socket but I don't use that currently). Playing around with alsamixer didn't help. Every control is unmuted and set to a decent volume (see attached amixer-contents files), but still no microphone echo. The software playthrough feature in Audacity seems to work, but it uses too much CPU for my slow Atom Z520 1.33 GHz, which results in skipping. Both PulseAudio's module-loopback and a pipe from arecord into aplay lag anywhere from 0.5 s to several seconds, which is too much for playing music. I tried the latency_msec argument for module-loopback and different options for arecord and aplay but couldn't reduce latency significantly. Also, I don't know why the delay varies so much during the same test run on an otherwise idle system. Have been googling all night. Many people encountered a similar problem. Apparently, with an AC97 sound card there is a control in alsamixer that enables mic feedback. But I couldn't find it in my own alsamixer -V all. If I have no luck with the hardware, a software solution will do as long as the delay constistently stays under, say, 10 ms. Any ideas? Where else should I look? I will be really grateful for any pointers. Hardware details: Asus Eee PC 1101HA netbook (Intel SCH US15W chipset) with two 3.5 mm mini-jack stereo sockets: one input and one output. The laptop also has a built-in microphone and speakers, but I don't use them. Software versions used: Linux 2.6.32 ALSA 1.0.22 PulseAudio 0.9.21-63-gd3efa-dirty Audacity 1.3.12-beta Ubuntu 10.04 More debugging info attached. -- Alexander
Attachment:
lsmod-grep-oss-snd-sound-hda
Description: Binary data
Attachment:
lsmod
Description: Binary data
Attachment:
ls-AlF-proc-asound
Description: Binary data
Attachment:
uname-a
Description: Binary data
Attachment:
lspci-vv
Description: Binary data
Attachment:
aplay-l
Description: Binary data
Attachment:
arecord-l
Description: Binary data
Attachment:
amixer-info
Description: Binary data
Attachment:
amixer-scontents
Description: Binary data
Attachment:
amixer-contents
Description: Binary data
Attachment:
cat-proc-asound-card0-codec#0
Description: Binary data
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