[pulseaudio-discuss] redirecting audio from SAA7134 tv card

Luca DELLA GHEZZA luca_dgh at hotmail.it
Thu Oct 1 10:38:22 PDT 2009

ok Tanu, first of all thx a lot for your reply.

I used pactl list to localize the correct input device, as well for the
output, but I'm not shure is the right one.
this is the output device I choose:
Sink #0
	Name: alsa_output.pci-0000_00_07.0.analog-stereo
	Description: Internal Audio Analog Stereo
	Driver: module-alsa-card.c
	Sample Specification: s16le 2ch 44100Hz
	Channel Map: front-left,front-right
	Owner Module: 6
	Mute: no
	Volume: 0:  88% 1:  88%
	        0: -3.33 dB 1: -3.33 dB
	        balance 0.00
	Base Volume: 100%
	             0.00 dB
	Monitor Source: alsa_output.pci-0000_00_07.0.analog-stereo.monitor
	Latency: 0 usec, configured 0 usec
		alsa.resolution_bits = "16"
		device.api = "alsa"
		device.class = "sound"
		alsa.class = "generic"
		alsa.subclass = "generic-mix"
		alsa.name = "ALC888 Analog"
		alsa.id = "ALC888 Analog"
		alsa.subdevice = "0"
		alsa.subdevice_name = "subdevice #0"
		alsa.device = "0"
		alsa.card = "0"
		alsa.card_name = "HDA NVidia"
		alsa.long_card_name = "HDA NVidia at 0xf9e78000 irq 21"
		alsa.driver_name = "snd_hda_intel"
		device.bus_path = "pci-0000:00:07.0"
		sysfs.path = "/devices/pci0000:00/0000:00:07.0/sound/card0"
		device.bus = "pci"
		device.vendor.id = "10de"
		device.vendor.name = "nVidia Corporation"
		device.product.id = "0774"
		device.product.name = "MCP72XE/MCP72P/MCP78U/MCP78S High Definition
		device.form_factor = "internal"
		device.string = "front:0"
		device.buffering.buffer_size = "65536"
		device.buffering.fragment_size = "32768"
		device.access_mode = "mmap+timer"
		device.profile.name = "analog-stereo"
		device.profile.description = "Analog Stereo"
		device.description = "Internal Audio Analog Stereo"
		alsa.mixer_name = "Nvidia MCP78 HDMI"
		alsa.components = "HDA:10ec0888,14627511,00100001
		module-udev-detect.discovered = "1"
		device.icon_name = "audio-card-pci"
		analog-output: Analog Output (priority. 10000)
		analog-output-headphones: Analog Headphones (priority. 9000)
	Active Port: analog-output

Anyway with this command

pactl load-module module-loopback
sink=alsa_output.pci-0000_00_07.0.analog-stereo rate=32000 format=s16le

I can ear the tv audio from the standard output. That is fantastic,
because I tried as well with the BT headset and it works.

Sadly the audio has a very poor quality:
1) the audio is pulsing, it seems that it pump up and down the master
2) the rate is wrong, because it seems an old 33 rpm listening at 45.

When I use sox to redirect audio it needs to set the rate to 32000, but
in this case has no effect.
I use s16le format because I know that the format used from the tv card
is Signed Little Endian 16 bit.
Finally I tried to change the latency to 1 and as well to 2000 but
nothing change, or very little changes.
I need different settings or may be I need to change the sink device?

> Where did you get that "pcm:0" string? I haven't used tvtime, but
> looking at its man page it looks like the part before the colon should
> be a path to an OSS mixer device, e.g. /dev/mixer, and the part after
> the colon should be one of a fixed set of strings, one of which is
> "line"

I'm not very experienced in audio devices, so I just read the tvtime
man, but probably I was not accurate.
Anyway now tvtime is capable to manage the mixer, because when I switch
on tvtime I listen the audio, when I switch it off the audio from tv
card is muted.

> Does Skype use pulseaudio for input? Are you running the newest 
> release of Skype that I hear finally works decently with pulseaudio?

Yes, I'm using the new Beta from Skype, and now the audio if perfectly
integrated in Pulseaudio. If it find Pulseaudio 0.9.15 or later it locks
the audio device management and leave everything to Pulse. This is
perfect because there only one location where to manage the audio
device. Furthermore, the cpu is not longer stressed when skype makes a
phone call.

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