[EMAIL PROTECTED] wrote: > Johannes Stezenbach <[EMAIL PROTECTED]> wrote: > > Audio is difficult, because I don't have a clue. We (== Convergence) > > currently do mixing via a simple OSS device, and I thought about the > > possibility of using parts of ALSA for more complex audio post > > processing options. > > > > If we could create an API which works for all of us I would like to include > > it in the DVB API. > > For audio h/w (e.g. DSP), status information would normally be returned in > a register or memory location. I guess > access to this register would have to be done via a read syscall or we > could setup an audio event to watch. OK, we would need to cater for AC-3, > LPCM, DTS, AAC, OGG, MPEG-1, MPEG-2 (inc. multichannel) and any other audio > standards. How do we want to proceed next?
Currently the audio API is very simple: - we can feed one stream into the audio decoder; possible formats include PCM, MPEG-Audio, AC3, AAC etc. - we take care of syncing audio to video (or to the STC) - we can start/stop decoding and mute/unmute Audio DSPs might have more capablilites for decoding and post-processing: - decoding more than one channel - wave audio playback - generating test tones - mixing channels and 5.1 individual channel volume control - bass/treble tone controls - multi-channel (5.1) decoding or downmixing - dynamic compression - 5.1 front/rear channel delay Additionally we have to control analog vs. digital audio outputs. Some of these possibly can be mapped to simple GET/SET-paramter ioctls. But you can also have a DSP firmware that offers independant functional blocks which can be connected in a flexible manner. That would complicate everything. I think ALSA has the capability to connect audio device blocks and to have a flexible set of audio device controls. But OTOH some of the audio features listed above are common to many DVB SoCs, so it might be a good idea to have support for them in the DVB API. Please Let me know what your requirements are wrt audio. Regards, Johannes -- Info: To unsubscribe send a mail to [EMAIL PROTECTED] with "unsubscribe linux-dvb" as subject.
