Unnecessary transcoding to Chromecast

Dev Community Apps & Creations
1

Hi there

 

Because my Synology NAS is transcoding too slowly, I did a reencoding of an mkv based to target format that is specified on the Chromecast codec reference:

https://developers.google.com/cast/supported_media_types

 

Version of Media Server is 0.9.8.6

 

Input:

MKV with:

Stream #0.0: Video: h264 (High), yuv420p, 1280x720, PAR 1:1 DAR 16:9, 23.98 fps, 23.98 tbr, 1k tbn, 47.95 tbc (default)
Stream #0.1(ger): Audio: ac3, 48000 Hz, stereo, s16, 192 kb/s (default)

 

So I did several tries in reencoding / remuxing the container and audio channel (I even tried MP3 encoding which is no option for me as it is only stereo):

/volume1/@appstore/MediaServer/bin/ffmpeg -i itn-dexter.s01e01.720p.mkv.back -vcodec copy -b:a 1600k -acodec libfaac -ac 6 dex.mp4

/volume1/@appstore/MediaServer/bin/ffmpeg -i itn-dexter.s01e01.720p.mkv.back -vcodec copy -b:a 1600k -acodec libfaac -profile:a aac_low -ac 6 dex.mp4

 

So at least the second remuxing to AAC with LC-AAC should fit. ffmpeg tells me now:

Stream #0.0(und): Video: h264 (High), yuv420p, 1280x720, 3753 kb/s, 23.98 fps, 23.98 tbr, 1k tbn, 47.95 tbc
Stream #0.1(ger): Audio: aac, 48000 Hz, 5.1, s16, 197 kb/s

 

I renamed the file and reloaded the media library. Plex now shown me the correct information (sorry for german output, but I think you're quiet familiar with the shown information):

 
Medien

Video Auflösung 720p
Dauer 53:01
Bitrate 3957 kbps
Width 1280
Height 720
Seitenverhältnis 1.78
Container MP4
Video Bildfrequenz 24p
Optimized For Streaming No



Datei


Accessible Yes
Exists Yes
Dauer 53:01
Datei /volume1/Plex/Media/Serien/Dexter/S01/itn-dexter.s01e01.720p/itn-dexter.s01e01.mp4
Size 1.47 GB
Container MP4
Has 64bit Offsets 0
Optimized For Streaming No



Video


Codec H264
Bitrate 3755 kbps
Bit Depth 8
CABAC 1
Chroma Subsampling 4:2:0
Color Space yuv
Dauer 53:01
Bildrate 23.976 fps
Frame Rate Mode vfr
Has Scaling Matrix 0
Height 720
Ebene 4.1
Profil high
Ref Frames 5
Scan Type progressive
Width 1280



Audio


Codec AAC
Kanäle 5.1
Bitrate 198 kbps
Sprache Deutsch
Bitratenmodus VBR
Dauer 53:01
Profil lc
Abtastfrequenz 48000 Hz
 

So I thought hooray, this should go trough, however the playback struggled all the time and my Synology NAS shown me 100% CPU usage with the new transcoder process running crazy (media indexing is NOT enabled).

 

The logs show me, that the media is getting transcoded:

Jan 11, 2014 16:00:31 [0xb192fb70] DEBUG - Using profile Chromecast
Jan 11, 2014 16:00:31 [0xb192fb70] DEBUG - Downloading document http://127.0.0.1:32400/library/metadata/20
Jan 11, 2014 16:00:31 [0xb192fb70] DEBUG - HTTP requesting to: http://127.0.0.1:32400/library/metadata/20
Jan 11, 2014 16:00:31 [0xb2856b70] DEBUG - Request: GET /library/metadata/20 [127.0.0.1:55598] (4 live)
Jan 11, 2014 16:00:31 [0xb2856b70] DEBUG - It took 0.000000 sec to serialize a list with 1 elements.
Jan 11, 2014 16:00:31 [0xb192fb70] INFO - Dexter - Dexter (S01E01): unable to obtain value for video.heigh
Jan 11, 2014 16:00:31 [0xb192fb70] DEBUG - Remuxing to dash/mp4/h264/aac
Jan 11, 2014 16:00:31 [0xb192fb70] DEBUG - Found session GUID of  in session start.
Jan 11, 2014 16:00:31 [0xb192fb70] DEBUG - Cleaning directory for session 4d062074-8ae5-4028-a1b8-ec603b13d501 (/volume1/Plex/tmp_transcoding/plex-transcode-4d062074-8ae5-4028-a1b8-ec603b13d501-027017d3-6561-4375-8c84-a615e06340a6)
Jan 11, 2014 16:00:31 [0xb192fb70] DEBUG - Starting a transcode session 4d062074-8ae5-4028-a1b8-ec603b13d501 at offset -1.0 (stopped=1)
Jan 11, 2014 16:00:31 [0xb192fb70] DEBUG - Job running: /volume1/@appstore/Plex Media Server/Resources/Plex New Transcoder -i http://127.0.0.1:32400/library/parts/115/file.mp4 -threads 0 -y -f dash -loglevel quiet -loglevel_plex error -map_metadata -1 -progressurl http://127.0.0.1:32400/video/:/transcode/session/4d062074-8ae5-4028-a1b8-ec603b13d501/progress -vcodec libx264 -crf 22 -maxrate 8000k -bufsize 16000k -vsi 0x0 -preset veryfast -x264opts cabac=0:me=dia:subme=0:me_range=4:no_chroma_me:8x8dct=0:bframes=0:rc_lookahead=1:qcomp=0.50:qpmin=10:qpmax=51:qpstep=4:partitions=none -min_segment_duration 3 -initial_segment 0 -force_key_frames expr:gte(t,n_forced*3) -map 0:0 -sn -acodec copy -map 0:1 dash
Jan 11, 2014 16:00:32 [0xb2e32b70] DEBUG - Request: GET /library/parts/115/file.mp4 [127.0.0.1:55599] (4 live)
Jan 11, 2014 16:00:32 [0xb2e32b70] DEBUG - Content-Length of /volume1/Plex/Media/Serien/Dexter/S01/itn-dexter.s01e01.720p/itn-dexter.s01e01.mp4 is 1573560188.
Jan 11, 2014 16:00:32 [0xb2e32b70] DEBUG - Request: GET /library/parts/115/file.mp4 [127.0.0.1:55600] (5 live)
Jan 11, 2014 16:00:32 [0xb2e32b70] DEBUG - Request range: 1571020993 to 0
Jan 11, 2014 16:00:32 [0xb2e32b70] DEBUG - Content-Length of /volume1/Plex/Media/Serien/Dexter/S01/itn-dexter.s01e01.720p/itn-dexter.s01e01.mp4 is 1573560188.
Jan 11, 2014 16:00:32 [0xb2856b70] DEBUG - Request: GET /library/parts/115/file.mp4 [127.0.0.1:55601] (4 live)
Jan 11, 2014 16:00:32 [0xb2856b70] DEBUG - Request range: 48 to 0
Jan 11, 2014 16:00:32 [0xb2856b70] DEBUG - Content-Length of /volume1/Plex/Media/Serien/Dexter/S01/itn-dexter.s01e01.720p/itn-dexter.s01e01.mp4 is 1573560188.
Jan 11, 2014 16:00:32 [0xb2856b70] INFO - [Transcoder] Input #0, mov,mp4,m4a,3gp,3g2,mj2, from 'http://127.0.0.1:32400/library/parts/115/file.mp4':
Jan 11, 2014 16:00:32 [0xb2e32b70] INFO - [Transcoder]     Stream #0:0(und): Video: h264 (High) (avc1 / 0x31637661), yuv420p, 1280x720, 3753 kb/s, 23.98 fps, 23.98 tbr, 1k tbn, 47.95 tbc
Jan 11, 2014 16:00:32 [0xb2856b70] INFO - [Transcoder]     Stream #0:1(ger): Audio: aac (mp4a / 0x6134706D), 48000 Hz, 5.1, fltp, 197 kb/s
Jan 11, 2014 16:00:32 [0xb2e32b70] DEBUG - [Transcoder] Average FPS ~ 24 fps, Frame rate ~ 24 fps.
Jan 11, 2014 16:00:32 [0xb192fb70] DEBUG -  [FFMPEG] Duration: 3181
Jan 11, 2014 16:00:32 [0xb192fb70] DEBUG - Read line, and done: 1
Jan 11, 2014 16:00:32 [0xb192fb70] DEBUG - Started session successfully: 4d062074-8ae5-4028-a1b8-ec603b13d501
Jan 11, 2014 16:00:32 [0xb2856b70] INFO - [Transcoder] Output #0, dash, to 'dash':
Jan 11, 2014 16:00:32 [0xb2e32b70] INFO - [Transcoder]     Stream #0:0: Video: h264 ([33][0][0][0] / 0x0021), yuv420p, 1280x720 [SAR 1:1 DAR 16:9], q=-1--1, 24k tbn, 23.98 tbc
Jan 11, 2014 16:00:32 [0xb192fb70] INFO - [Transcoder]     Stream #0:1: Audio: aac ([64][0][0][0] / 0x0040), 48000 Hz, 5.1, 197 kb/s
Jan 11, 2014 16:00:32 [0xb2856b70] DEBUG - Request: PUT /video/:/transcode/session/4d062074-8ae5-4028-a1b8-ec603b13d501/progress?width=1280&height=720 [127.0.0.1:55609] (5 live)
Jan 11, 2014 16:00:32 [0xb2856b70] DEBUG -  * width => 1280
Jan 11, 2014 16:00:32 [0xb2856b70] DEBUG -  * height => 720
Jan 11, 2014 16:00:32 [0xb2856b70] DEBUG - DASH segment range: -1 - -1

So my question is - what am I doing wrong? I think I have the correct container (MP4), the correct video (H264) and audio (AAC, LC-AAC) encodings. This should go trough without any transcoding?

 

Any help is very appreciated,

Joel

2

What client are you casting from? You should check your client's bitrate settings for local playback. I had to change my Android settings to "Maximum" for Over Local Network before casting to the Chromecast didn't transcode.

3

Hi Blatan

Thanks for your answer. The client was on iOS (iPhone). I just did a repackaging of the newest Plex Media Server for my DS214play and now it works like a charm. I think the profile wasn't set up properly and is fixed with the newest release (didn't find anything in the changelog so far).

Regards

Joel

4

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