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Chromecast and AC3 passthrought


eraser8

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eraser8

Hi,

 

Since Chromecast allow AC3 passthrougt, when do you think you will update the Chromecast profile to send directly the AC3 track without transcoding?

 

Currently, I'm able to to only direct stream a MP4 (H.264) with AAC audio codec. When I try with AC3 audio codec, MB transcode entire stream and it sucks a lot of juice on my HTPC

 

Thanks

 

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Thanks for the info. A have added support for this to our chromecast receiver. Please help test this. You'll need to reboot your chromecast device in order to get the updated receiver.

 

@@Luis if you don't mind reviewing that'd be great too, thanks.

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eraser8

Hi Luke,

 

Thanks for that. Is this fix already in release? Which version? It would be a pleasure for me to help you by testing it if I can Dow load the good version of the server.

 

Thanks a lot

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eraser8

Hi Luke,

 

So, If I understand weel the Chromecast process, when I turn on the Chromecast, the MB server detect it and go to fetch online (maybe on your server) the Chromecast profile to determine what the Chromecast can do or not. It is right?

 

Although, I have tested the Chromecast and now I cannot send anything to mine. I tried many types of movie, music (mp3) , Live TV, ...... Nothing is casted.

Maybe it's a problem on my side but it worked before.

 

Thanks Luke

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eraser8

Hi Luke,

 

Update:  Now, I'm able to cast on my chromecast. I don't know why it didn't work but anyway. I tried to play  a MP4 file containing MPEG4 and AAC. There is no problem to direct play this type of file. I just tried to play an MP4 containing a MPEG4 video with an AC3 audio stream but it did not Direct stream. It transcode it entirely. So, maybe your change should be more accurate for the Chromecast profile?

 

Also, I noticed one thing about casting MP4 (Mpeg4 + AAC). I extract the info from MEDIAINFO. Some are able to be Direct streamed and some not:

 

 

DIRECT STREAM WORKS: 

 

ID                                       : 1
Format                                   : AVC
Format/Info                              : Advanced Video Codec
Format profile                           : High@L4.1
Format settings, CABAC                   : Yes
Format settings, ReFrames                : 4 frames
Codec ID                                 : avc1
Codec ID/Info                            : Advanced Video Coding
Duration                                 : 1h 53mn
Bit rate                                 : 2 500 Kbps
Maximum bit rate                         : 13.3 Mbps
Width                                    : 1 920 pixels
Height                                   : 1 080 pixels
Display aspect ratio                     : 16:9
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)                       : 0.050
Stream size                              : 1.98 GiB (89%)
Writing library                          : x264 core 118 r2085 8a62835
Encoding settings                        : cabac=1 / ref=4 / deblock=1:0:0 / analyse=0x3:0x133 / me=umh / subme=9 / psy=1 / psy_rd=1.00:0.00 / mixed_ref=1 / me_range=16 / chroma_me=1 / trellis=2 / 8x8dct=1 / cqm=0 / deadzone=21,11 / fast_pskip=1 / chroma_qp_offset=-2 / threads=9 / sliced_threads=0 / nr=0 / decimate=1 / interlaced=0 / bluray_compat=0 / constrained_intra=0 / bframes=3 / b_pyramid=2 / b_adapt=2 / b_bias=0 / direct=3 / weightb=1 / open_gop=0 / weightp=2 / keyint=250 / keyint_min=23 / scenecut=40 / intra_refresh=0 / rc_lookahead=60 / rc=2pass / mbtree=1 / bitrate=2500 / ratetol=1.0 / qcomp=0.60 / qpmin=0 / qpmax=69 / qpstep=4 / cplxblur=20.0 / qblur=0.5 / vbv_maxrate=50000 / vbv_bufsize=50000 / nal_hrd=none / ip_ratio=1.40 / aq=1:1.00
Encoded date                             : UTC 2014-04-06 06:14:26
Tagged date                              : UTC 2014-04-06 06:15:24
 

 

 

DIRECT STREAM DOES NOT WORK:

 

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                                 : avc1
Codec ID/Info                            : Advanced Video Coding
Duration                                 : 1h 53mn
Bit rate                                 : 2 500 Kbps
Maximum bit rate                         : 15.3 Mbps
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)                       : 0.068
Stream size                              : 1.98 GiB (89%)
Writing library                          : x264 core 129 r2230 1cffe9f
Encoding settings                        : cabac=1 / ref=5 / deblock=1:0:0 / analyse=0x3:0x133 / me=umh / subme=9 / psy=1 / psy_rd=1.00:0.00 / mixed_ref=1 / me_range=16 / chroma_me=1 / trellis=2 / 8x8dct=1 / cqm=0 / deadzone=21,11 / fast_pskip=1 / chroma_qp_offset=-2 / threads=12 / lookahead_threads=2 / sliced_threads=0 / nr=0 / decimate=1 / interlaced=0 / bluray_compat=0 / constrained_intra=0 / bframes=3 / b_pyramid=2 / b_adapt=2 / b_bias=0 / direct=3 / weightb=1 / open_gop=0 / weightp=2 / keyint=250 / keyint_min=23 / scenecut=40 / intra_refresh=0 / rc_lookahead=60 / rc=2pass / mbtree=1 / bitrate=2500 / ratetol=1.0 / qcomp=0.60 / qpmin=0 / qpmax=69 / qpstep=4 / cplxblur=20.0 / qblur=0.5 / vbv_maxrate=50000 / vbv_bufsize=50000 / nal_hrd=none / ip_ratio=1.40 / aq=1:1.00
Encoded date                             : UTC 2014-09-23 17:45:19
Tagged date                              : UTC 2014-09-23 17:45:41
 

 

 

 

One difference I've noticed is the CABAC value is different ( REF=4 works but REF=5 doesn't works).

Hope this could help

 

Thanks

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cyberbuzz23

Hi, would be nice to have all codec available for chromecast passthrough. I have lot of lag when is not passtrough i think because my cpu is at 100% 

 

Thx folks

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eraser8

For Direct streaming to Chromecast, you need to follow what the Chromecast is able to decode or passthrough(audio). Check this link to know more about what media is supported.

 

https://developers.google.com/cast/docs/media

 

In brief, MP4 with AAC or AC3(passthrough) are currently supported by Chromecast

 

 

 

Luke, if you have a way for me to test it individually, I can test it for you with pleasure.

 

Thanks a lot

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eraser8

Great! Now the .MP4 with AC3 audio is now working in Direct Stream!! Thanks Luke!

 

 

For the other question above (about REF=5 that doesn't work in direct stream) have you investigate it? I just retest it and it Transcode instead of DS

 

Amazing time of response from you BTW! :)

Edited by eraser8
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eraser8

Hi Luke,

 

On the media that doesn't direct stream here is the line that corespond to Ref frame=5

Format settings, ReFrames                : 5 frames

 

 

For the media that works in Direct stream, the Ref Frame is 4:

Format settings, ReFrames                : 4 frames

 

 

 

So, currently, I guess the Chromecast profile on the receiver is limit to only 4. ? If you could put it to 5, I could test it right now.

 

Thanks

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cyberbuzz23

Sorry my bad. Forget the WebM container... it's not exacly MKV. If you have mkv you have to reencode it to WebM if you want direct streaming. I'll just make all my video with MP4 container. Bye bye MKV

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eraser8

So MKVs don't direct play, even with AC3?

 

No, this container is not supported by chromecast. Only MP4 and WebM..... for now. Crossfinger that Google will add more media support in future release.

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Latchmor

Strange because in testing last night Luke and I had H264 / AC3 in a MKV direct streaming... Video perfect but no audio. Annoying that it seemed so close.

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Latchmor

no MKV supported at all

 

Sorry, just in case my comment to CBers confused the issue. Luke and I were trying another version of the MB Chromecast Receiver page during our testing, not the one that's active just now. It was his other version that we got close to MKV direct but just couldn't get the audio.

 

He had to put it back to the original version which transcodes so it didn't break for other people.

 

Cheers

Edited by Latchmor
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