Re: [alsa-devel] [PATCH 0/3] ALSA: snd-usb: Some small fixes to make Playback Design products work
On 03/24/2013 03:50 AM, Andreas Koch wrote:
rate for PCM. If you plug that DAC into a Mac, the Mac will automatically select 705.6kHz for PCM and then nothing will work because the DAC doesn't support that in PCM. So then, the DAC would have to define 2 complete interfaces: one for PCM and one for DSD. That
OK, the difference is that I don't use UAC2 at all, but completely different protocol. So what I'm talking about is only how it looks from the driver towards the application...
DoP could be implemented similar way inside the UAC driver using for example snd_pcm_hw_rule_add() between SNDRV_PCM_HW_PARAM_FORMAT and SNDRV_PCM_HW_PARAM_RATE. And maybe enabled as quirks?
There are many devices having constraints between rate and channels. In this case we just have a constraint between rate and formats.
Looking at the UAC driver there seems to be something a bit related: /* FIXME: there is no AC3 format defined yet */ // fp->formats = SNDRV_PCM_FMTBIT_AC3; fp->formats = SNDRV_PCM_FMTBIT_U8; /* temporary hack to receive byte streams */
- Jussi
On 24.03.2013 11:50, Jussi Laako wrote:
On 03/24/2013 03:50 AM, Andreas Koch wrote:
rate for PCM. If you plug that DAC into a Mac, the Mac will automatically select 705.6kHz for PCM and then nothing will work because the DAC doesn't support that in PCM. So then, the DAC would have to define 2 complete interfaces: one for PCM and one for DSD. That
OK, the difference is that I don't use UAC2 at all, but completely different protocol. So what I'm talking about is only how it looks from the driver towards the application...
What protocol is that? Is there a driver for Linux?
Daniel
On 03/26/2013 09:34 PM, Daniel Mack wrote:
What protocol is that? Is there a driver for Linux?
Just a custom flow-controlled bulk-mode byte stream. I have some hacks to make things work for my own prototype purposes, but I haven't got time to make anything clean and worth releasing.
There's not much point in releasing a driver that nobody else has hardware for... :)
I was hoping to discuss the ALSA sample format topic already earlier in context of getting DSD support to the RigiSystems USBPAL Linux driver, but it doesn't seem to be proceeding anywhere and I don't have necessary documentation (nor time)... https://github.com/lintweaker/mytekusb2 I have the hardware though, so I can test & develop things at application side.
- Jussi
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Daniel Mack -
Jussi Laako