On Mon, Oct 03, 2022 at 09:26:31AM +0200, Alexandre Ratchov wrote: > On Thu, Sep 22, 2022 at 04:31:58PM +0000, adr wrote: > > Hi, > > > > first of all, I've never contributed to the xine project, and > > I don't have any experience with sndio, so bear with me... > > > > Frustrated with the bad sound playing a 6 channels aac audio I decided to > > take a look. The device is a usb one: > > > > $ dmesg | grep -i audio > > uaudio0 at uhub2 port 3 configuration 1 interface 1 "GeneralPlus USB Audio > > Device" rev 1.10/1.00 addr 6 > > uaudio0: class v1, full-speed, sync, channels: 2 play, 1 rec, 8 ctls > > audio0 at uaudio0 > > uhidev2 at uhub2 port 3 configuration 1 interface 3 "GeneralPlus USB Audio > > Device" rev 1.10/1.00 addr 6 > > > > It has only 2 channels for playback. > > > > The file has 5.1 aac audio: > > $ ffprobe file.mp4 > > [...] > > Stream #0:1(eng): Audio: aac (LC) (mp4a / 0x6134706D), 48000 Hz, 5.1, fltp, > > 224 kb/s (default) > > [...] > > > > Xine's ffmpegaudio plugin is supposed to do downmix (please, correct > > me if I'm wrong), but: > > > > $ xine --verbose=2 file.mp4 > > [...] > > audio_out: ao_open (0x585415540) > > audio_sndio_out: ao_sndio_open bits=16 rate=48000, mode=128 > > audio_sndio_out: ao_sndio_open 6 channels output > > [...] > > > > The code in xine-lib-1.2.12/src/audio_out/audio_sndio_out.c by Brad > > Smith is following the recommendations at sio_open(3), there is no > > problem there. > > > > sio_getpar() is returning 6 channels as valid, so the sound ends > > messed up. The right speaker gets mostly ambient sound and the > > voices are almost only audible through the left speaker. > > > > mplayer and mpv have means to force downmix, but xine is the only > > media player which can play 1080p h264 video with a decent performance > > (if the bitrate is not too high) on an rpi4 (no hardware acceleration, > > cpu at 2.2Gz) > > > > One workaround for this particular case could be adding the > > configuration setting "audio.output.speaker_arrangement" to > > audio_sndio_out.c. > > > > I'm using the last snapshot: > > > > $ doas sysupgrade -ns > > Fetching from https://ftp.OpenBSD.org/pub/OpenBSD/snapshots/arm64/ > > SHA256.sig 100% |************************************************| 1544 > > 00:00 Signature Verified > > Already on latest snapshot. > > > > base72.tgz 21-Sep-2022 11:41 262659517 > > > > Is this behaviour normal and I'm just missing something? > > Some thoughts? > > Hi, > > This is a known problem. While mpv and mplayer have options to turn > the downmixing, it's not OK this to be manual. ???
Cannot parse. If you cannot write this in english, please say what's going on in french. > IMHO, the most appropriate (and probably simplest) is to extend sndiod > to do the surround conversions, so the problem would be solved at > system level and all players would benefit (as we do for all other > conversions, btw). Less code, less bugs. As far as I know, we still need to address liba52 levels. Last time I checked, nobody but aja and I were concerned, and we couldn't figure out (on most AC3 videos, sndio levels are 100% subpar). Also, I'm questionning where master.level=1.00 makes sense. In many many cases the application doesn't do more, but sndio could (possibly) boost to 200% and be fine. Moonshot: I was promised a land where sndio would take over audio(4) and where I could get hardware AC3 through sndio. I have an USB sndcard that should deliver this. How far away are we from the promise ? I couldn't care less about "real time" mixing. I really want surround sound on video...
