Server Version#: 1.21.1.3876
Player Version#: 4.50.1
Noticed today that when using Plex on Chrome that ALAC files always transcode to AAC.
I have the same issue on 2 desktop machines (a Mac Mini running OS X, the other an HP laptop running Windows 10). I don’t experience the same issue using the desktop app on Mac, which direct plays ALAC as I would expect. Same for my Android phone, direct plays ALAC as expected.
Different Plex clients have different capabilities, based on the capabilities and limitations of the underlying player, hardware, and what is licensed by the manufacturer. What direct plays on one client may not direct play on another.
Plex web is limited by the capabilities of the browser. Chrome does not support ALAC, so Plex has to transcode it to a supported format. Chrome does not support HEVC video either. If you play a HEVC video using Plex Web via Chrome, it will be transcoded to H.264.
Plex for Windows/Mac is built using the mpv video player. It is much more capable than Plex Web. As you’ve found out, it will direct play most audio and video formats, including ALAC and HEVC.
Somebody from Plex will have to answer that question. I’m not aware of a user configurable option.
Plex Web on Chrome/Windows does direct play FLAC, so maybe ALAC → FLAC would be an option.
Unfortunately there is no clearinghouse of what formats are supported on what clients.
Safari direct plays ALAC on my Macbook. Microsoft Edge on Windows 10 does not. I have not tried Firefox, Brave, or other browsers.
Hopefully others can weigh in with their experiences.
For music, you might take a look at Plexamp, https://plexamp.com/. It is a multi-platform music player that plays music stored on your Plex Media Server. I have not used it a lot, but it seems to direct play ALAC. When I play a ALAC song it says “playing” in the Plex dashboard. It does not say “Direct Play,” but neither does it say “Transcoding.”
I would expect Plex to prioritise transcoding to another lossless format like FLAC when possible in preference of lossy like AAC, which it doesn’t appear to do in this case. Would be helpful if someone from Plex could chime in to answer that.
I use Plexamp when I can. In the case of my HP Laptop, it’s a work machine that I don’t have installation privileges for, so I’ve been using Chrome browser as a workaround.
Using Plexamp, when I play an ALAC file, the Plex dashboard specifies Audio ALAC (English Stereo). As you’ve explained, it doesn’t specify Direct Play but I’ve taken it to mean that it is direct as it isn’t being transcoded.
