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by rp1301
Tue Jan 15, 2013 9:36 am
Forum: Troubleshooting
Topic: USB performance: Isochronous (audio or video)
Replies: 21
Views: 16443

Re: USB performance: Isochronous (audio or video)

Tested with USB video capture device dmesg: [27353.470043] usb 1-1.2: new high-speed USB device number 9 using dwc_otg [27353.600678] usb 1-1.2: New USB device found, idVendor=0ac8, idProduct=3610 [27353.600709] usb 1-1.2: New USB device strings: Mfr=1, Product=2, SerialNumber =0 [27353.600726] usb ...
by rp1301
Tue Jan 15, 2013 1:51 am
Forum: Troubleshooting
Topic: USB performance: Isochronous (audio or video)
Replies: 21
Views: 16443

Re: USB performance: Isochronous (audio or video)

Here is the lsmod. Module Size Used by snd_bcm2835 13018 0 snd_usb_audio 104097 0 snd_usbmidi_lib 18067 1 snd_usb_audio snd_hwdep 5929 1 snd_usb_audio snd_seq_midi 4591 0 snd_seq_midi_event 6544 1 snd_seq_midi snd_rawmidi 21160 2 snd_usbmidi_lib,snd_seq_midi snd_pcm 77560 2 snd_bcm2835,snd_usb_audio...
by rp1301
Mon Jan 14, 2013 1:52 pm
Forum: Troubleshooting
Topic: USB performance: Isochronous (audio or video)
Replies: 21
Views: 16443

Re: USB performance: Isochronous (audio or video)

USB audio capture again. Have reliable capture without needing dwc_otg.speed=1 when the USB card does stereo capture. Only mono devices need dwc_otg.speed=1 for reliable capture. Tested all permutations of 3 x mono cards, 2 x stereo cards, on 2 x RPi, with & without Ethernet active. Completely repea...
by rp1301
Sat Jan 12, 2013 10:27 pm
Forum: Troubleshooting
Topic: USB performance: Isochronous (audio or video)
Replies: 21
Views: 16443

Re: USB performance: Isochronous (audio or video)

Further to the USB audio capture dropped data...

Booting with kernel option

dwc_otg.speed=1

cures the problem. Capture works reliably then.
by rp1301
Fri Jan 11, 2013 3:59 pm
Forum: Troubleshooting
Topic: USB performance: Isochronous (audio or video)
Replies: 21
Views: 16443

Re: USB performance: Isochronous (audio or video)

C-Media based sound cards fail to capture correctly. USB data loss, around 1% of the data is silently dropped. A USB device which delivers a measured (on a PC) 47999.1 samples/sec, when used on the Pi, delivers an erratic 47500 +/- 300 samples/sec. Period size, buffer size, nrpacks settings make no ...

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