On 20. 08. 24 9:37, Shengjiu Wang wrote:
On Tue, Aug 20, 2024 at 2:59 PM Pierre-Louis Bossart
<pierre-louis.bossart@xxxxxxxxxxxxxxx> wrote:
On 8/20/24 04:53, Shengjiu Wang wrote:
On Mon, Aug 19, 2024 at 3:42 PM Pierre-Louis Bossart
<pierre-louis.bossart@xxxxxxxxxxxxxxx> wrote:
On 8/16/24 12:42, Shengjiu Wang wrote:
Implement the ASRC memory to memory function using
the compress framework, user can use this function with
compress ioctl interface.
Define below private metadata key value for output
format, output rate and ratio modifier configuration.
ASRC_OUTPUT_FORMAT 0x80000001
ASRC_OUTPUT_RATE 0x80000002
ASRC_RATIO_MOD 0x80000003
Can the output format/rate change at run-time?
Seldom I think.
If no, then these parameters should be moved somewhere else - e.g.
hw_params or something.
This means I will do some changes in compress_params.h, add
output format and output rate definition, follow Jaroslav's example
right?
yes, having parameters for the PCM case would make sense.
I am still not very clear on the expanding the SET_METADATA ioctl to
deal with the ratio changes. This isn't linked to the control layer as
suggested before, and there's no precedent of calling it multiple times
during streaming.
Which control layer? if you means the snd_kcontrol_new? it is bound
with sound card, but in my case, I need to the control bind with
the snd_compr_stream to support multi streams/instances.
I can only quote Jaroslav's previous answer:
"
This argument is not valid. The controls are bound to the card, but the
element identifiers have already iface (interface), device and subdevice
numbers. We are using controls for PCM devices for example. The binding
is straight.
Just add SNDRV_CTL_ELEM_IFACE_COMPRESS define and specify the compress
device number in the 'struct snd_ctl_elem_id'.
"
I don't think it is doable, or at least I don't know how to do it.
My case is just one card/one device/one subdevice. can't use it to
distinguish multi streams.
I already wrote that the compress core code should be extended to support
subdevices like other ALSA APIs. I'll work on it. For now, just add support
for one converter.
Jaroslav
--
Jaroslav Kysela <perex@xxxxxxxx>
Linux Sound Maintainer; ALSA Project; Red Hat, Inc.
