[lug] (Raspberry Pi) media center control?

[Michael J. Hammel]

On Sat, 2021-06-12 at 13:10 -0600, Davide Del Vento wrote:
> Is bluetooth DAC the same as sending bluetooth audio to a receiver,
> or is it different? Google does not clarify.
> Wikipedia mentions A2DP as bluetooth audio, and nothing as bluetooth
> in https://en.wikipedia.org/wiki/Digital-to-analog_converter
> 
> That would work, has anybody tried it? Suggestions for hardware or
> software?

I bought a bluetooth transmitter that I hacked into our original TV
trailer TV (see https://www.rpawd.com/mods/wireless-speakers/).  Works
fine to transmit audio from the TV to bluetooth speakers.  However,
there is noticable lag when watching a video and listening to the
speakers.  In the end, this lag was not acceptable.  

The TV was stolen out of the trailer which, along with the failed
bluetooth speaker project, led me to build the PiBox Media System which
can play videos or serve them over a closed wifi network using samba.

> Does anything similar exist for the phone screen, so I can be spared
> of the HDMI cable too? Or is that too much bandwidth?

It's likely much easier to transmit video files over wifi than try to
transmit HDMI without cables.  ffmpeg used to have ffserver, but it's
been dropped with the latest releases.  You could use ffmpeg
transcoding to convert to mjpeg and stream a file, but I think just
sharing the file over a network and letting the remote end play the
file is simpler.  That makes decoding of the file the players problem
and not a streaming/transmission problem.

Video files over 802.11g works fine.  I do it all the time.  802.11b
works okay if you're not doing above 720p video.  If you're trying to
server (or stream) 4K60 video you're gonna want wired connections.

> I see. That still seems overkill to me as the other suggestions. 
> Perhaps I can instead use the Pi just to store the files and access
> them from the phone over the home network, without doing the
> streaming part.

Bingo.  If you're on the local network (inside your house) and the
video files are 720p or less then you can just stream them from a plex
server.  If they're larger than 720p plex can convert for you on the
fly but the Pi3 might be a bit taxed doing that.  Maybe.  Ideally you
want the videos in the best format for their use case.  You can use
ffmpeg to convert them as needed.

FWIW, I have Plex on an AMD box (2 cores/8GB, but being upgraded to 4
cores/32GB cuz the old box is, well, reeeally old and dying) and all my
DVDs ripped (using MakeMKV) to 10TB drives connected to a RPi.  The Pi
is the file server.  The AMD box is the Plex server, which just has the
Pi drives mounted over NFS.  I'm currently looking into switching to a
Pi as the plex server but only if I can get it running on PiBox and
only if it handles transcoding (converting the files on the fly for
optimum streaming on the local network) effectively.

If it's just you using the plex server I think the Pi3 might be okay. 
If, like me, you have others using the server at the same time as you
then it's hard to say if it's sufficient.  Plex may not have hw
accelerated decoding/encoding on the Pi (though the omxplayer I use in
PiBox does).  I haven't dived that deep into that particular project
yet.

-- 
Michael J. Hammel
mjhammel at graphics-muse.org
michaelhammel at acm.org