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Unnecessary Transcoding from Chromecast Ultra


JulioQc
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JulioQc

Hello,

 

I recently moved from Plex to Emby because the first still doesn't support the Chromecast Ultra but I'm coming across a different problem with Emby:

While most video files I have are 5.1 or 7.1 audio tracks and thus require transcoding, which I know is normal for the CCU since it only supports stereo audio or passthrough, I notice Emby transcodes the whole file instead of only the audio... So because the MKV has 5.1 audio, the video is transcoded from HEVC to h264 all the time which obviously uses unnecessary CPU and lowers the quality of the stream. 

 

This occurs for any HEVC files I have that includes an audio track over 2 channels... HD or UHD. 

 

So is this normal? Did I forget to configure anything? Where can I get more info as to why exactly it's being transcoded? 

post-231031-0-01353900-1501856907_thumb.png

emby_server.log

emby_transcoding.log

Edited by JulioQc
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mastrmind11

Hello,

 

I recently moved from Plex to Emby because the first still doesn't support the Chromecast Ultra but I'm coming across a different problem with Emby:

While most video files I have are 5.1 or 7.1 audio tracks and thus require transcoding, which I know is normal for the CCU since it only supports stereo audio or passthrough, I notice Emby transcodes the whole file instead of only the audio... So because the MKV has 5.1 audio, the video is transcoded from HEVC to h264 all the time which obviously uses unnecessary CPU and lowers the quality of the stream. 

 

This occurs for any HEVC files I have that includes an audio track over 2 channels... HD or UHD. 

 

So is this normal? Did I forget to configure anything? Where can I get more info as to why exactly it's being transcoded? 

check and post the transcode logs from that session.

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JulioQc

Edited my post to include required logs and a picture of the dashboard status. 

 

So you can see it says the transcoding is caused by incompatible audio, which is fine but the video is also converted to h264 for some reason.... 

 

This is the video info:

Codec HEVC
Profile Main 10
Level 150
Resolution 3840x2160
Aspect ratio 16:9
Anamorphic No
Interlaced No
Framerate 25
Bitrate 34918 kbps
Pixel format yuv420p10le
Ref frames 1

This is compatible with the CCU I believe but note how the level is detected as 150 instead of 5.0

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JulioQc

To follow up, I've converted the audio to AAC 5.1 and it direct play now :)

 

So ya, ok DTS needs transcoding but why is the video transcoded as well? And why not to h265?

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  • 2 months later...

Hi,

 

This unnecessary transcoding happens with Chromecast 2 also, Log attached.

 

That's not exactly true. The bitrate of your video is over 12mbps. It's well documented that Chromecast can only handle 10-11 mbps, so that is why it's transcoding. For Chromecast Ultra, the limit is much higher.

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maestrozezinho

That's not exactly true. The bitrate of your video is over 12mbps. It's well documented that Chromecast can only handle 10-11 mbps, so that is why it's transcoding. For Chromecast Ultra, the limit is much higher.

 

Plex can cast this file transcoding only the audio.

 

Plex also plays the following file direct streaming the video and transcoding only the audio:

General
Unique ID                                : ******************
Complete name                            : ******************.mkv
Format                                   : Matroska
Format version                           : Version 2
File size                                : 18.2 GiB
Duration                                 : 1 h 5 min
Overall bit rate mode                    : Variable
Overall bit rate                         : 40.0 Mb/s
Encoded date                             : UTC 2011-02-17 11:14:07
Writing application                      : mkvmerge v4.5.0 ('Speed of Light') built on Jan 31 2011 22:54:33
Writing library                          : libebml v1.2.0 + libmatroska v1.1.0

Video
ID                                       : 1
Format                                   : AVC
Format/Info                              : Advanced Video Codec
Format profile                           : High@L4.1
Format settings                          : CABAC / 4 Ref Frames
Format settings, CABAC                   : Yes
Format settings, RefFrames               : 4 frames
Codec ID                                 : V_MPEG4/ISO/AVC
Duration                                 : 1 h 5 min
Bit rate mode                            : Variable
Maximum bit rate                         : 40.0 Mb/s
Width                                    : 1 920 pixels
Height                                   : 1 080 pixels
Display aspect ratio                     : 16:9
Frame rate mode                          : Constant
Frame rate                               : 23.976 (24000/1001) FPS
Color space                              : YUV
Chroma subsampling                       : 4:2:0
Bit depth                                : 8 bits
Scan type                                : Progressive
Title                                    : ************** @ 37976 kbps
Language                                 : English
Default                                  : Yes
Forced                                   : No
Color range                              : Limited
Color primaries                          : BT.709
Transfer characteristics                 : BT.709
Matrix coefficients                      : BT.709

Audio
ID                                       : 2
Format                                   : DTS
Format/Info                              : Digital Theater Systems
Format profile                           : MA / Core
Mode                                     : 16
Format settings, Endianness              : Big
Codec ID                                 : A_DTS
Duration                                 : 1 h 5 min
Bit rate mode                            : Variable / Constant
Bit rate                                 : Unknown / 1 509 kb/s
Channel(s)                               : 6 channels
Channel positions                        : Front: L C R, Side: L R, LFE
Sampling rate                            : 48.0 kHz
Frame rate                               : 93.750 FPS (512 SPF)
Bit depth                                : 16 bits
Compression mode                         : Lossless / Lossy
Title                                    : DTS (MA) / 2073 kbps / 48 KHz / 16-Bit / 5.1
Language                                 : English
Default                                  : Yes
Forced                                   : No

Edited by maestrozezinho
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Plex doesn't check if the bitrate is too high before casting. By searching their forum you'll see many people experiencing 'lag' issues because of that. 

Emby might check that first before casting but I couldn't say for sure. 

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@@JulioQc, this topic was originally about chromecast ultra. The above member has taken us off topic a little by posting about older models, but Chromecast Ultra has a slightly different set of rules and it should be direct playing quite a bit more.

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  • 6 months later...
DungHo51

I just recently found out about emby. installed and got premier. I'm very excited to cast my first music video to chromecast ultra. Soon after the cast I got disappointed because of the audio stuttering/lag (DTS 5.1).  I'm hoping Emby get this issue resolved soon. I also used Videostream and have no such problem. Emby just have an awesome interface and organization for all the media. I'm hoping to switch over to Emby for good but the audio issue needs to be resolved first. 

 

thanks

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Hi, can you try dropping the Chromecast quality setting to 3 mbps? This will force a full video transcode. Please see if that helps. Thanks !

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DungHo51

Thanks, i will try later today and report back. although I do prefer direct stream to get the best quality. Any thoughts on what is the cause. I know Plex and Videostream both able to playback DTS 5.1 perfectly fine to my chromecast ultra. Been using all 3 and I like emby best, would rather stay with Emby

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Well the audio will have to be converted because Chromecast does not support dts. We could potentially try lowering the audio bitrate.

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DungHo51

Luke, tried changing the chromecast to 3mb. It is still not working. Audio sounds broken like yesterday I investigated a little more now that i know the program. Looks like it is transcoding already. So I'm guessing the problem is the transcoder. 

Edited by DungHo51
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