AC3 Transcoding

[JaScoMa 34]

Hello..

I've been testing different server configurations because of an issue I've run into; plus I wanted to see if there's a difference between my normal configuration using software transcoding and one which uses hardware transcoding..  This issue occurs with either stable or beta releases.

 

My normal server setup is a RockPro64 which uses software transcoding.  I also tried a QNAP TS-451+ setup which uses hardware transcoding (decided against this setup because the CPU gets very warm (150 degrees) and the fan runs at almost 1400rpm).  Tonight, I installed emby server to my nVidia Sheild which uses hardware transcoding.

 

The issue is I have Band of Brothers as blu-ray MKV rips; I re-ripped them last night to ensure there weren't any issue with the MKVs.  There are only two audio channels available.  When I first select any episode, the two channels shown by emby are English DTS-HD MA 5.1 (default) and English DTS 5.1.  This doesn't seem to matter which channel I select to use.

As you can see in the screen shot below, the dashboard sees the audio as AC3.  Anyway, even with hardware transcoding, the transcoding isn't transcoding fast enough and the buffer ends up being chewed up.  So after about 2 minutes of play time, the video starts stopping and restarting while the buffer fills up.  Obviously with the RockPro64 because of software transcoding, the stopping and restarting occurs very soon after the video starts.

These seem to be the only MKVs I've found which I have this issue with.  I've attached the logs and transcode logs from the nVidia server for review.

 

Thanks..

 

 

embyserver.txt

ffmpeg-transcode-4fb2e16b-e962-4732-820f-7bd4eaacc620_1.txt

[Luke 42078]

Hi, is there a question?

[JaScoMa 34]

Yes, why is transcoding not working properly with these MKV's?  No other MKV does this.

 

I tried the webview and same thing; transcode buffer couldn't create enough of a buffer so the video kept stopping and starting.

 

Edited January 30, 2020 by JaScoMa

[Happy2Play 9780]

Does the setup support DTS?  Not sure why VC1 is not flagged also.  But that codec is just as difficult as HEVC to work with.  The hardware would appear to not be powerful enough to keep up with playback looking at the frames per second (23).

&VideoCodec=h264,mpeg2video,hevc,h265
&AudioCodec=ac3,aac,mp3

&TranscodeReasons=AudioCodecNotSupported

22:11:59.252 Stream mapping:
22:11:59.252   Stream #0:0 -> #0:0 (vc1 (native) -> h264 (h264_mediacodecndk))
22:11:59.252   Stream #0:1 -> #0:1 (dts (dca) -> ac3 (native))

Edited January 30, 2020 by Happy2Play

[Luke 42078]

Vc1 input is always going to be significantly slower to transcode. I would consider converting that file.

[ebr 16183]

Hi.  Emby is converting your Audio to AC3 (Dolby Digital) because your playback system does not support DTS (or DTS HD).  Then, because the video is VC1 - which cannot be delivered via a remux - we have to also transcode the video and your server is just not powerful enough to keep up with that.

 

Does that explain what is happening for you?

[JaScoMa 34]

Yes it does.  Thank you everyone for your assistance.

 

Was VC1 an older way which they encoded for blu-rays?  Seems like newer blu-rays are h.264 nowadays.

[Luke 42078]

Vc1 is far less common, yes.