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Buffer/Pausing when streaming to Chrome Web UI / FFMPEG hammering CPU


Concept211
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Concept211

I've been experiencing streaming issues in the last couple of weeks. It used to stream fast and smooth and now even when i turn the quality down to the point where it's almost unwatchable (144p), it still pauses/buffers. I'm running a AMD A8 quad-core 3.0GHz cpu w/ 16GB of ram and when I monitor the system, ffmpe.exe is maxing out all 4 cores.


 


Did something change in the transcoding configuration because I've been using MB/Emby for years and never had an issue before. In fact, I used to run it on a slower system (3-cores, lower cpu speed and half the ram) about a year ago and it still ran flawlessly.


 


Here are my logs:


 


Server log:


http://paste2.org/sYwc2ZM5


 


Transcoding log:


http://paste2.org/jJ3kb31n


 


Any help is greatly appreciated!


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plazma

Yip big back end changes, Luke said one of the big changes is now they can support multi threaded transcodes. Turn on throttling it may likely help keep the cpu use down if its not already on, also (in mybexperience) just setting transcode to performance instead of auto or best quality is perfectly watchable and shave a bit more overhead.

 

There was a bug/issue a few beta builds back where ffmpeg was launching as low priority instead of normal, I wrote a script that I looped every 60 seconds to elevate it to normal to work around the issue (my lack of cpu power) however as you have a bigger chip you could potentially use it and mod the vbs so it dropped the ffmpeg threads to low, so it wasn't fighting system resources, but honestly its a fudge, try throttling setting first ;-)

 

Also if you have a boat load/spare ram (depending on what quality you want to transcode at) you could transcode into a ram drive. for me where the virtual machines on a disk already with heavy disk io it made a big difference.

 

Also it was suggested by someone else (Luke is already aware), they had a similar issue and manually installed the latest ffmpeg build and it helped them, post here:

http://emby.media/community/index.php?/topic/19243-transcoding-using-100-cpu/

Although try my first two suggestions first, or/and wait for Luke to look into it further.

 

Sorry my bad you already discovered it :-(

Edited by plazma
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Concept211

Hey Plazma,

 

Thanks so much for the info!

 

I'll try the throttle option tomorrow and see, but as I recall i think it's only for throttling the max bitrate so I doubt it would affect the CPU usage since I've tried turning down the video quality as low as possible.

 

 

I would love to try your vbs script if you could share it with me... Much appreciated!

 

I wasn't even aware that you can create a virtual drive with your spare ram... That's a great idea! I'll have to try that s well since the system never utilizes all of it.

 

Thanks again! Hopefully we'll hear back from Luke as well :)

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plazma

On my system throttle does appear to drop the transcode (@1.5mbps) to around 70% instead of decking the cpu, I sent you a pm with the vbs, like I said its a fudge so I wont post in public as it not something most people should do/need, but im happy to share if people want.

 

As for ram disk, if your running in windows on a bear metal system imdisks a good free choice (again pm me for it) but you can easily script to bring it up on boot.

 

Ive fairly limited number of users and capped all off at 1.5mbps max and im using 3.5gb for ram transcode and it works great.

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Concept211

Wow... Loving all of this info. Thanks again!

 

Yes, please pm me with the ram disk info. I'll def implement it because I know that's another bottleneck in my system.

 

Also, which setting do you have the transcoded section set at? Auto or fast transcoding with lower quality?

 

Thanks!

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plazma

im setting performance (higher speed) in transcode setting :-)

 

at @ 1.5mbps 720p its perfectly watchable even on a big tv, more is always going to look better, but it allows me less overhead.

 

No worries, always happy to help out another emby user.

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Concept211

Thanks again for all of the tips and instructions. Unfortunately, none of it has helped although I haven't tried the virtual machine option. I thought that having the ram disk would really make a difference, but nothing :(  The only thing that seems to help is to set the -threads parameter to 1 in the ffmpeg.exe command line. Unfortunately, it doesn't seem like it's configurable anywhere in the emby server files.  

 

It's so frustrating because it used to work great. I remember when you first started a stream ffmpeg.exe used to just spike for a few seconds at 100% and then go way down and everything streamed and ran great. Now it's unusable.  :(

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plazma

Ram disk for transcode will only help disk io issues, most people shouldn't need it although on an ssd based system its gona save you some disk wear, i would go down the vm route, that way you can give the vm half your cores or all of your cores and then just cap the cpu level as a work around for the time being, im sure Luke is already working on a solution ;-) 

 

Most of the time as others said your best to do the transcode as quickly as possible and get it out the way, however if its not a dedicated server and your fighting for system resources the vm route will give you what you want in a round about way and reduce the load back to meet your needs.

 

Obviously leave your data/media where/as it sits and just point the vm to the shares.

 

Don't have a spare windblows licence just rock a Linux vm for the host, but that said a windows emby install/host is just a little easier to configure in my experience.

 

Virtualbox is your best/simple free option, in case you have not got much experience with vms this is a good place to start: https://www.virtualbox.org/manual/ch01.html

 

Downloads here: https://www.virtualbox.org/wiki/Downloads

Get the extension pack as well ;-)

 

But if you do try and you get stuck drop me a pm, im happy to help.

Edited by plazma
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Concept211

awesome -- you're the man, @@plazma !  

 

I'll probably hold out for a bit until the devs are able to come up with a fix. After all, none of this is truly urgent ;) 

 

Thanks again for all of your help! I'm sure I'll be picking your brain soon enough ;)

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