On 16/03/11 07:31, Patrick Lai wrote:
Hi,
Is there a precedent for playback/capture compressed audio stream through ALSA playback/capture interface if underlying hardware supports decoder + sink & encoder + source capabilities?
No. (Apart from AC3 passthrough to spdif output)
ALSA might be extended to cope with compressed audio with fixed frame size and bitrate, but dealing with any VBR encoding is likely to be even more problematic.
This is because alsa assumes a fixed relationship between samplerate and data rate, and also assumes that samples fit in an integer number of bytes.
AFAIK dealing with hardware enc/dec has been done using gstreamer plugins. E.g. http://www.lca2010.org.nz/slides/50315.pdf
Given that audioscience makes cards that support mp3 encode/decode as well as pcm, I'd like it if alsa *did* support compressed audio...
Which source file can I find an example?
Thanks Patrick
regards