I’m running Version 1.7.2.3878 on Nvidia Shield. When watching a recording on the same Nvidia Shield, I notice that the video is DirectStream and the audio is transcoding AC3 to AAC. By quick skip, I mean that while playing back, I press the “right” button and there is a bit of a delay; the skip is not instantaneous. I’m comparing this to my experience of watching recordings through the HDHomeRun app on the Nvidia Shield.
I wonder why Plex is transcoding from AC3 to AAC. I assume that the Shield can play AC3 to the TV since the HDHomeRun app isn’t transcoding but playing the file directly.
Any suggestions on how to disable the AC3 transcoding so I can test whether that is causing the sluggishness when skipping?
HDHR could of added AC3 transcoding in their app to play back files like this.
I highly doubt it’s an audio problem but if you enable passthrough it should try to do direct play. you can turn on ‘Display Information’ to see what its doing in the upper left hand corner.
I turned on the “Display Info” and the following message was shown:
Video Direct, Audio Transcode, Transcode Reason: AC-3 audio is not supported by the device
I plugged the Shield into my receiver and verified it does Direct Play for video and audio. Keeping the Shield connected to the receiver, I disabled Pass-through and it reverted back to transcoding (and the same display message above) and the slight delays when skipping returned.
In theory, is pass-through mode required to use AC-3? When pass-through is enabled and being used, it disables the volume control on the Shield saying:
This app is set for surround sound. Use the TV remote to adjust the volume.
I have seen this on the Amazon app, but haven’t seen it on the HDHomeRun app.
The skipping is definitely much snappier when both audio and video are Direct Play, so the audio transcoding is what is causing the delays when skipping.
I have a setup in which the TV is too old support AC3, and I can leave passthrough on and it still direct plays connected to the TV, without a receiver, both audio and video.
Passthrough is required to not having AC3 be transcoded.
But you also shouldn’t be having this much issues w/ transcoded audio either…
FYI: this is just reporting back info; No need to resolve here. I’ve commented on other threads regarding this transcoding behavior and suggestions to improve the user experience.
I have a setup in which the TV is too old support AC3, and I can leave passthrough on and it still direct plays connected to the TV, without a receiver, both audio and video.
Do your files contain AC3 audio track or AAC audio track? I have verified that my TV does not support AC3 decoding and files that have AAC audio direct play for me as well. In all my tests of AC3 files, AC3 gets transcoded to AAC by the Plex server because the TV doesn’t support it.
When connected to an AVR that does support AC3 decoding, Plex Server will transcode the audio if passthrough is disabled to send as AAC, but won’t transcode if passthrough is auto to send as AC3.
HDHR could of added AC3 transcoding in their app to play back files like this.
Yes, I used VLC and verified through its logs that it’s decoding AC3 in their app. I now suspect HDHR is doing the same.
