[pulseaudio-discuss] Digital input on Creative Sound Blaster X-FI HD

[Oddbjørn Norstrand]

Hi

I am having problems recording from digital input on a Creative Sound
Blaster X-FI HD. Recordings work using alsa, but I only receive
samples with value zero when using pulseaudio.

This is the source from pacmd list-sources:
   index: 3
        name: <alsa_input.usb-Creative_Technology_USB_Sound_Blaster_HD_000000tf-00.iec958-stereo>
        driver: <module-alsa-card.c>
        flags: HARDWARE DECIBEL_VOLUME LATENCY DYNAMIC_LATENCY
        state: RUNNING
        suspend cause: 
        priority: 9048
        volume: front-left: 65634 / 100% / 0.04 dB,   front-right: 65634 / 100% / 0.04 dB
                balance 0.00
        base volume: 65536 / 100% / 0.00 dB
        volume steps: 65537
        muted: no
        current latency: 0.17 ms
        max rewind: 0 KiB
        sample spec: s16le 2ch 44100Hz
        channel map: front-left,front-right
                     Stereo
        used by: 1
        linked by: 1
        configured latency: 40.00 ms; range is 0.50 .. 2000.00 ms
        card: 1 <alsa_card.usb-Creative_Technology_USB_Sound_Blaster_HD_000000tf-00>
        module: 7
        properties:
                alsa.resolution_bits = "16"
                device.api = "alsa"
                device.class = "sound"
                alsa.class = "generic"
                alsa.subclass = "generic-mix"
                alsa.name = "USB Audio #1"
                alsa.id = "USB Audio"
                alsa.subdevice = "0"
                alsa.subdevice_name = "subdevice #0"
                alsa.device = "1"
                alsa.card = "2"
                alsa.card_name = "USB Sound Blaster HD"
                alsa.long_card_name = "Creative Technology USB Sound Blaster HD at usb-0000:00:14.0-2, full speed"
                alsa.driver_name = "snd_usb_audio"
                device.bus_path = "pci-0000:00:14.0-usb-0:2:1.0"
                sysfs.path = "/devices/pci0000:00/0000:00:14.0/usb2/2-2/2-2:1.0/sound/card2"
                udev.id = "usb-Creative_Technology_USB_Sound_Blaster_HD_000000tf-00"
                device.bus = "usb"
                device.vendor.id = "041e"
                device.vendor.name = "Creative Technology, Ltd"
                device.product.id = "3232"
                device.product.name = "USB Sound Blaster HD"
                device.serial = "Creative_Technology_USB_Sound_Blaster_HD_000000tf"
                device.string = "iec958:2"
                device.buffering.buffer_size = "352800"
                device.buffering.fragment_size = "176400"
                device.access_mode = "mmap+timer"
                device.profile.name = "iec958-stereo"
                device.profile.description = "Digital Stereo (IEC958)"
                device.description = "USB Sound Blaster HD Digital Stereo (IEC958)"
                alsa.mixer_name = "USB Mixer"
                alsa.components = "USB041e:3232"
                module-udev-detect.discovered = "1"
                device.icon_name = "audio-card-usb"
        ports:
                iec958-stereo-input: Digital Input (S/PDIF) (priority 0, latency offset 0 usec, available: unknown)
                        properties:

        active port: <iec958-stereo-input>

When I configure the the sound card to off in tab Configuration in
pavucontrol this command works giving me a out.wav file with nonzero
samples.
ffmpeg -f alsa -i hw:2,1 -t 30 out.wav

When I configure the digital input in pavucontrol and try this command
I get a recording where all samples are zero.
parec --device=alsa_input.usb-Creative_Technology_USB_Sound_Blaster_HD_000000tf-00.iec958-stereo --format=s16le --rate=44100 --channels=2 > samples

Can anyone see what is wrong or help me further investigate the
problem?