[alsa-devel] S/PDIF and track markers (echo3g)
Hi,
Is there any provision in ALSA (either within the kernel or libasound) for extracting track marker information from S/PDIF?
I have a large number of MiniDisc recordings to preserve as FLAC format.
Losing track markers would be a huge inconvenience, though I don't care for the rest of the metadata (track names etc..)
There's enough recordings to be worth developing specific software for the archival if it can access this information.
I don't really know which path is likely to be successful:
* An ALSA API to access the information; though I can't see anything specific to track markers
* Whether a timecode could be used to detect track change; but I can't see any in /proc/asound/Layla3G/status
* Does ALSA provide access to raw AES streams, so I could decode it in userland? I'm un-sure if this relates to hardware AC3 decoding.
* Maybe this sort of status is only available to the firmware of the interface and never makes it to userland (in my case, echo3g); though I can see some constants relating to 'non audio' S/PDIF.
The hardware I have here is Echo Layla 3G (snd-echo3g) and a Pioneer MJ-D707 MiniDisc recorder.
Any advice appreciated -- many thanks.
17.06.2016, 16:29, Mark Hills kirjoitti:
Hi,
Hi,
Is there any provision in ALSA (either within the kernel or libasound) for extracting track marker information from S/PDIF?
I don't know what track marker data looks like, but see below.
I have a large number of MiniDisc recordings to preserve as FLAC format.
Losing track markers would be a huge inconvenience, though I don't care for the rest of the metadata (track names etc..)
There's enough recordings to be worth developing specific software for the archival if it can access this information.
I don't really know which path is likely to be successful:
An ALSA API to access the information; though I can't see anything specific to track markers
Whether a timecode could be used to detect track change; but I can't see any in /proc/asound/Layla3G/status
Does ALSA provide access to raw AES streams, so I could decode it in userland? I'm un-sure if this relates to hardware AC3 decoding.
ALSA does provide access to the raw stream with drivers that support that. You'll need to record with IEC958_SUBFRAME_LE or IEC958_SUBFRAME_BE sample formats.
- Maybe this sort of status is only available to the firmware of the interface and never makes it to userland (in my case, echo3g); though I can see some constants relating to 'non audio' S/PDIF.
Unfortunately the echo3g driver doesn't seem to support IEC958_SUBFRAME_* sample formats.
The HDA driver, used for most mainboard/laptop integrated audio, does support that format if the hardware is capable. I'm not sure if the hardware commonly supports that format or not, though.
The hardware I have here is Echo Layla 3G (snd-echo3g) and a Pioneer MJ-D707 MiniDisc recorder.
Any advice appreciated -- many thanks.
On Fri, 17 Jun 2016, Anssi Hannula wrote:
17.06.2016, 16:29, Mark Hills kirjoitti:
Hi,
Hi,
Is there any provision in ALSA (either within the kernel or libasound) for extracting track marker information from S/PDIF?
I don't know what track marker data looks like, but see below.
I have a large number of MiniDisc recordings to preserve as FLAC format.
Losing track markers would be a huge inconvenience, though I don't care for the rest of the metadata (track names etc..)
There's enough recordings to be worth developing specific software for the archival if it can access this information.
I don't really know which path is likely to be successful:
An ALSA API to access the information; though I can't see anything specific to track markers
Whether a timecode could be used to detect track change; but I can't see any in /proc/asound/Layla3G/status
Does ALSA provide access to raw AES streams, so I could decode it in userland? I'm un-sure if this relates to hardware AC3 decoding.
ALSA does provide access to the raw stream with drivers that support that. You'll need to record with IEC958_SUBFRAME_LE or IEC958_SUBFRAME_BE sample formats.
Thanks, that's very useful information.
- Maybe this sort of status is only available to the firmware of the interface and never makes it to userland (in my case, echo3g); though I can see some constants relating to 'non audio' S/PDIF.
Unfortunately the echo3g driver doesn't seem to support IEC958_SUBFRAME_* sample formats.
Ah, as I'd suspect. And probably there is a lot of logic in the firmware that would have to cooperate.
The HDA driver, used for most mainboard/laptop integrated audio, does support that format if the hardware is capable. I'm not sure if the hardware commonly supports that format or not, though.
This is the hardware I have on my motherboard, but it doesn't have the optical input I would need.
Perhaps I can find a reasonably priced PCI Express card with the capability.
Thanks for your help, I have a feeling this is the most promising route. But it does assume the MiniDisc deck is outputting this information (it definitely acknoledges it on input)
The hardware I have here is Echo Layla 3G (snd-echo3g) and a Pioneer MJ-D707 MiniDisc recorder.
Any advice appreciated -- many thanks.
Thanks
participants (2)
-
Anssi Hannula -
Mark Hills