At Mon, 2 Aug 2010 14:33:38 -0500, pl bossart wrote:
Looked at gstreamer, it seems to only have ac3-in-iec61937 support currently. However, I'd guess gstreamer would additionally need some ways to 1) detect if HBR is supported, and 2) detect if the connected receiver supports the specific codec..
Reusing the existing IEC958 status bits is OK for practical POV, indeed. This makes also compatible with the existing user-space stuff.
But I feel a bit uncertain when looking forward for future development. More discussions needed.
The automatic detection is not possible for now no matter if you rely on gstreamer or ffmpeg or something else. The one thing that is missing for HDMI is to make use of EDID information to report to userspace the capabilities of the receiver so that apps or the audio policy make educated decisions on whether to decode locally or use pass-through modes using iec61937. The HDMI spec only mandates stereo/48kHz, and if you have an older receiver (2 years old...) you may not have TruHD supported there. To the best of my knowledge, there aren't any standard controls to report what the receiver supports. I had some discussions with Takashi on this in the past, looks like it's time to make this happen?
Yeah, good chance to really implement something. We certainly need some solid channel for the extra information like EDID.
Takashi