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Question about chromecast


KRA

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I have tried several different media codecs and containers. But it always transcode.

I'm on server Versjon 3.0.5518.4 installed on ubuntu 14.04.1 using chrome/web ui to client.

 

This is massive waste of resource and create a lot of unwanted heat in the server.

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@@Luke "That's not a bug that's a feature :/"

 

IMHO it's not working as intended.

 

If your car is using 10 times the amount of fuel that is needed, wouldn't you say something is broken ?

If you work hard for an hour to achieve something that can be done in seconds, wouldn't you say your doing something wrong ?

 

I have confirmed files playing on chromecast fine without need of transcoding, however MBS always does full transcode. Whatever container/codec/bitrate is used it transcode to seemingly the same quality settings, and same video codec ( except it caps at 10mbit for bitrate). It also transcode DTS audio (chromecast supported) into AAC audio.

 

Original video codec that plays fine (but is transcoded anyways) :

 

 

Video
ID                             : 1
Format                         : AVC
Format/Info                    : Advanced Video Codec
Format profile                 : High@L4.1
Format settings, CABAC         : Yes
Format settings, ReFrames      : 5 frames
Codec ID                       : V_MPEG4/ISO/AVC
Duration                       : 1h 55mn
Bit rate                       : 9 296 Kbps
Width                          : 1 920 pixels
Height                         : 800 pixels
Display aspect ratio           : 2.40:1
Frame rate mode                : Constant
Frame rate                     : 23.976 fps
Color space                    : YUV
Chroma subsampling             : 4:2:0
Bit depth                      : 8 bits
Scan type                      : Progressive
Bits/(Pixel*Frame)             : 0.252
Stream size                    : 7.35 GiB (84%)
Writing library                : x264 core 144 r2525 40bb568
Encoding settings              : cabac=1 / ref=5 / deblock=1:0:0 / analyse=0x3:0x133 / me=umh / subme=7 / psy=1 / psy_rd=1.00:0.00 / mixed_ref=1 / me_range=16 / chroma_me=1 / trellis=1 / 8x8dct=1 / cqm=0 / deadzone=21,11 / fast_pskip=0 / chroma_qp_offset=-2 / threads=18 / lookahead_threads=3 / sliced_threads=0 / nr=0 / decimate=1 / interlaced=0 / bluray_compat=0 / constrained_intra=0 / bframes=3 / b_pyramid=2 / b_adapt=1 / b_bias=0 / direct=1 / weightb=1 / open_gop=0 / weightp=2 / keyint=250 / keyint_min=23 / scenecut=40 / intra_refresh=0 / rc_lookahead=40 / rc=2pass / mbtree=1 / bitrate=9296 / ratetol=1.0 / qcomp=0.60 / qpmin=0 / qpmax=69 / qpstep=4 / cplxblur=20.0 / qblur=0.5 / ip_ratio=1.40 / aq=1:1.00
Language                       : English
Default                        : Yes
Forced                         : No
 
Audio
ID                             : 2
Format                         : DTS
Format/Info                    : Digital Theater Systems
Mode                           : 16
Format settings, Endianness    : Big
Codec ID                       : A_DTS
Duration                       : 1h 55mn
Bit rate mode                  : Constant
Bit rate                       : 1 509 Kbps
Channel(s)                     : 6 channels
Channel positions              : Front: L C R, Side: L R, LFE
Sampling rate                  : 48.0 KHz
Bit depth                      : 24 bits
Compression mode               : Lossy
Stream size                    : 1.22 GiB (14%)
Language                       : English
Default                        : Yes
Forced                         : No

 

What it is transcoded into:

 

 

Video
ID                             : 256 (0x100)
Menu ID                        : 1 (0x1)
Format                         : AVC
Format/Info                    : Advanced Video Codec
Format profile                 : High@L4.1
Format settings, CABAC         : Yes
Format settings, ReFrames      : 4 frames
Codec ID                       : 27
Duration                       : 6s 6ms
Width                          : 1 920 pixels
Height                         : 800 pixels
Display aspect ratio           : 2.40:1
Frame rate mode                : Variable
Color space                    : YUV
Chroma subsampling             : 4:2:0
Bit depth                      : 8 bits
Scan type                      : Progressive
 
Audio
ID                             : 257 (0x101)
Menu ID                        : 1 (0x1)
Format                         : AAC
Format/Info                    : Advanced Audio Codec
Format version                 : Version 4
Format profile                 : LC
Muxing mode                    : ADTS
Codec ID                       : 15
Duration                       : 5s 994ms
Bit rate mode                  : Variable
Channel(s)                     : 6 channels
Channel positions              : Front: L C R, Side: L R, LFE
Sampling rate                  : 48.0 KHz
Compression mode               : Lossy
Delay relative to video        : -75ms
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chromecast is known to reliably support up to 4 refframes, sorry. Your video has 5 and maybe in your case it could actually direct stream, but right now 4 is considered the safe rule of thumb for Chromecast.

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@@Luke ok that is a valid concern, even though I have not had issues.

 

And after doing some research I understand why I'm not having issues. 4 reframes is a limitation of L4.1@1080p

 

However the movie above is 1920x800 and as I understand is within the limits even if it's using 5 reframes.

 

Also as far as I can tell, 4 reframes is not a limit of chromecast it's the limit of L4.1 @ 1080p specs, if you go down to ex 720p 5 reframes is well within specs. (9 is limit at 720p)

 

But 720p also end up being transcoded, did someone misinterpret 4 reframes as a definitive chromecast limit ?

Edited by KRA
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cherno_cba

I have the same issue here. I can play a file without transcoding using Videostream for chrome, but if I use MediaBrowser it does the transcoding, and I end with high cpu usage, and worse image quality. 

 

Video
Codec H264
Profile High
Level 31
Resolution 720x404
Aspect ratio 16:9
Anamorphic No
Interlaced No
Framerate 23.97602
Bitrate 682 kbps
Bit depth 8 bit
Pixel format yuv420p
Ref frames 5
CABAC Yes
 
Chromecast is able to transcode a 720p or 1080p file, so why shouldn't be able to play a 480p ??? 
Isn't Chromecast supposed to play h264 up to level 4.1? 
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Ref frames 5
 
 
Chromecast is able to transcode a 720p or 1080p file, so why shouldn't be able to play a 480p ??? 
Isn't Chromecast supposed to play h264 up to level 4.1? 

 

 

@@cherno_cba @@Luke

 

 

It is, the problem here seems to be that MBS reads the "Ref frames 5", and automaticly transcode, because at full 1080p Ref frames 4 is max to keep within the 4.1 specs.

 

As I also wrote here: http://mediabrowser.tv/community/index.php?/topic/17611-chromecast-and-ac3-passthrought/page-2&do=findComment&comment=177643

At lower resolution higher Ref frames should be no problem, this is also my experience.

 

Hopefully they will tweak chromecast settings soon so we don't have to transcode fully compatible audio and video streams.

Edited by KRA
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