Experiment: Option to transcode surround sound audio to AC3#947
Experiment: Option to transcode surround sound audio to AC3#947damontecres wants to merge 6 commits into
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damontecres
added
enhancement
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Merged this to 0.5.1 release and tested on Yamaha ARC receiver + Sony Android TV. When playing AAC 5.1 it will convert it to AC3 5.1 and play beautifully on receiver as it should, but there are downsides as you mentioned. When this conversion occurs it indeed does seems to do something with video somewhere - i don't have explanation for this except black magic. From what I can see in Jellyfin server logs it just direct stream (copy) video , transcode audio to ac3 (-codec:a:0 ac -ac 6 -ab 640000) a send it. This is especially jarring when using/changing subtitles. Maybe problem on Wholphin side? Also I managed to break this fix entirely when transcoded video started playing, i changed audio to basic AC3 track in another language and activated subtitles there - then returned audio to original AAC track and activated subtitles ... AAC collapsed to PCM 2.0 and video no longer transcoded :D Kinda wondering if the changes in DeviceProfileUtils.kt would not be the culprit. |
What do you mean? Like the video is glitching?
Oh yeah. There's some special logic when switching tracks if direct play is occurring. It will bypass using the device profile to check with the server if the newly selected tracks are direct playable from ExoPlayer's perspective. Not sure if I explained that well enough, but I know where to fix this in the code. |
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I'm very interested in this PR, since I have a S/PDIF connection with my receiver. And I currently can't use Wholphin because of this.
I either won't be able to use subtitles or videos will always be transcoded together with audio? |
If the audio is being transcoded, then if you enable an embedded subtitle track, it will switch the video to transcode as well in order to burn-in the subtitles. But, I still need to investigate a bit more because I believe this situation happens because the transcoded stream is |
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I see. Thanks for explaining! |
Just annoying waiting time every time you change something because of the transcode issue. Sorry for confusion :) |
@n8llcaster The latest commit, 5d6b8ff, should fix this now. I'll eventually need to figure out a better, more generalized way to handle this type of "unsupported" track, but for now, this should work. |
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First of all, thanks to the creators of WHOLPHIN for the best app I've tried for Jellyfin 👍 I tried everything to transcode OPUS 5.1 and AAC 5.1 on Smart TVs (Android TV, LG webOS, and Samsung Tizen) to use the SPDIF and HDMI ARC outputs. On Android, the only external players that worked were Kodi and Vimu Media Player. I installed the experimental WHOLPHIN version and enabled AC3 transcoding, but it didn't work on my Smart TV running Google TV 12. |
This change forces all multichannel audio to be transcoded to AC3 5.1. This is meant for TV's/devices that support SPDIF and/or ARC, but not eARC. Therefore they are limited to 6 channels and the AC3 codec (many such devices support DTS codec as well, but not as universally as AC3). However, they frequently advertise support for more channels and newer codecs, silently downmixing such audio streams internally. This change ensures that the client can still output multichannel audio that is compatible with the device. This change does not force video transcode, or alter existing video stream transcoding behavior. This change primarily: 1. Adds a toggle to enable this mode. 2. Manages potentially conflicting 'Downmix to Stereo' and 'AC3 Supported' toggles. 3. For video libraries, if toggle is enabled, sets max channels to 6 and invalidates all non-AC3 codecs for multichannel audio. 4. For music libraries, if toggle is enabled, sets max channels to 6 and requests transcode to AC3 in mka container for multichannel audio. Similar to Experimental PR damontecres#947. 1. UT's added to validate and prevent potential toggle conflicts. 2. Manually tested on Firestick 4k (1st gen) in video+audio libraries: - Stereo audio content plays with DirectPlay - Multichannel AC3 content plays with DirectPlay - Multichannel non-AC3 content plays with DirectStream N/A LLM's were used for planning, initial draft and critical review. All code changes were manually reviewed and vetted.
4 participants
This is an experiment and may not be merged!
Description
Adds a toggle (ugh) to prefer transcoding AAC/OPUS audio with more than 2 channels to AC3. Stereo AAC does not transcode.
This is basically a workaround for HDMI ARC (not eARC) or optical audio devices because instead of 2 uncompressed PCM channels, 6 AC3 channels (ie 5.1) is possible.
An downside of enabling this is that embedded subtitles be burned in causing a video transcode as well.
Related issues
Fixes #255
Testing
Just on the emulator so far to observe if the settings trigger the transcode or not
Screenshots
N/A
AI or LLM usage
None