[alsa-devel] HW decoding abstracted in ALSA
Hi,
I am new to ALSA and audio stack in Linux. I have a sound card that can do HW decoding as well. I am looking at writing an ALSA driver such that whatever may be the player or MMF above, it should use the HW decoder and not the inherit SW decoder that is available with the player.
Can someone help me with some pointers or existing like-drivers?
Thanks in advance, Harsha
At Mon, 25 Feb 2008 12:27:00 +0530, Harsha priya gupta wrote:
Hi,
I am new to ALSA and audio stack in Linux. I have a sound card that can do HW decoding as well. I am looking at writing an ALSA driver such that whatever may be the player or MMF above, it should use the HW decoder and not the inherit SW decoder that is available with the player.
Can someone help me with some pointers or existing like-drivers?
Which format is in mind? In theoery, you can implement the h/w decoder on the ALSA framework, but there are some restrictions:
- ALSA PCM assumes the constant bitrate - The format bit must be defined - The specific app recognizes and supports that format
In the case of AC3 or DTS, it's embedded in SPDIF frames so the PCM core stuff doesn't take care of the above. But, in the case of native (non-PCM) formats, the support can be difficult as is.
Takashi
Hi Takashi,
Can you help quantify the 'difficult' part that you have mentioned here?
Would I be right if I say that it requires additional APIs implementation in ALSA framework and ALSA Libasound to be implemented? Or is there any other path that we should be following?
I am copying Krishna to this email who is working with me in this project. She would like to correspond with you as well in this regard.
Thanks, Harsha.
On Mon, Feb 25, 2008 at 5:33 PM, Takashi Iwai tiwai@suse.de wrote:
At Mon, 25 Feb 2008 12:27:00 +0530, Harsha priya gupta wrote:
Hi,
I am new to ALSA and audio stack in Linux. I have a sound card that can
do
HW decoding as well. I am looking at writing an ALSA driver such that whatever may be the player or MMF above, it should use the HW decoder
and
not the inherit SW decoder that is available with the player.
Can someone help me with some pointers or existing like-drivers?
Which format is in mind? In theoery, you can implement the h/w decoder on the ALSA framework, but there are some restrictions:
- ALSA PCM assumes the constant bitrate
- The format bit must be defined
- The specific app recognizes and supports that format
In the case of AC3 or DTS, it's embedded in SPDIF frames so the PCM core stuff doesn't take care of the above. But, in the case of native (non-PCM) formats, the support can be difficult as is.
Takashi
participants (2)
-
Harsha priya gupta -
Takashi Iwai