Subsonic Forum

by **pcs800** » Mon Jan 10, 2011 5:47 pm

I have subsonic running on a server which is on a 20 meg line, no bandwidth issues there. When streaming to my phone (android), there is ALWAYS buffering, stop, buffering, stop, etc.
I have set the server to limit bandwidth, and also tried no limit. No difference.
The phone gets about 1.5 down, so it should be plenty fast enough.

Also, as of lately, when a song stops to buffer, it will start from the beginning rather than continuing on where it left off, any help appreciated.

by **GJ51** » Mon Jan 10, 2011 6:28 pm

No easy answer here. Ther are a lot of variables and it takes a lot of experimenting to find the right combination for each situation. I've been testing for quite a few weeks and have a few observations.

Transcoding takes a lot of cpu power and the process can slow down the transfer rate eventhough bandwidth is adequate. The best way to bypass transcoding on the fly for Android is to format video for mobile into flv. That way the stream is just output to the phone without any cpu load. Even when your doing that, results over 3g are inconsistent and vary greatly depending on signal strength. I've had tests where I've streamed DVD's using on the fly transcoding and had them play fine, then I've had tests where any transcoded and flv material just pauses continuously.

Over Wifi, inside my network, everything works great except HD quality movies that are transcoded on the fly. I think that is the result of the transcoding load just being too heavy for the cpu to keep up with the output stream.

So, in general, I think HD quality transcoding is limited by CPU power on the server. Even lower resolution videos may be affected by transcoding depending on the power of the server. I have a quad core Xeon 2.83GHz CPU, but ffmpeg only uses one core per video stream for transcoding. If you have less cpu power, you'll most likely see problems at resolutions lower than HD.

So the first limiting factor is cpu power, which can be avoided by formating your mobile video into flv to stream directly to the phone. If you do that, then the next factors are bandwidth. Your band width numbers look good, so that shoudn't be a problem.

The last issue is the phone itself. No matter how fast or slow you send data, the phone has to process it. Different phones will have different capabilities for displaying the range of resolutions transmitted to the phone.

As an illustration, I was out of town over New Year's and tested watching HD video through Subsonic. I got good results using a new Dell XPS with good graphics and a 1920X1080 screen. I had to let the video download buffer for a few minutes before playback, but if I did the movie would play through. Trying to do the same thing on my old Toshiba laptop that is 7 years old didn't achieve the same results. Even though the data was buffered, the graphics engine on the old laptop just couldn't do the playback without frequent pauses.

Conclusion: Subsonic has the potential to deliver video to various platforms under various conditions, but the user needs to understand and adjust as needed to get satisfactory results for the unique setting and equipment being used.

by **pcs800** » Mon Jan 10, 2011 6:44 pm

I am sorry for not being specific. I am not talking about video, just audio. All files are in mp3 format ranging from 128kb/s to 320kb/s

by **GJ51** » Mon Jan 10, 2011 6:59 pm

Then you most likely have a Droid.

by **pcs800** » Mon Jan 10, 2011 7:25 pm

Yes that's why I put "android" in the original post.
So I am guessing by the short response that you do not have a droid and don't have any other help to offer?

by **GJ51** » Mon Jan 10, 2011 7:36 pm

http://forum.subsonic.org/forum/viewtop ... highlight=

I have an Android phone, but it's an EVO 4g not a Motorola Droid.

by **pcs800** » Mon Jan 10, 2011 7:55 pm

Mine is an HTC Hero

by **pcs800** » Mon Jan 10, 2011 7:59 pm

Also, the file start over thing never happened before. It's always been fine, meaning if it stops to buffer, it would continue on, not start over like it has recently been doing. I have been using subsonic for over a year and the android app for quite a few months, never had an issue like this.

by **GJ51** » Mon Jan 10, 2011 8:09 pm

The symptoms your describing are typical of low 3g download speed. Does the same thing happen over wifi?

by **pcs800** » Mon Jan 10, 2011 8:12 pm

Yes, I can connect at home or at work to a wireless router and it still happens. Granted my home speed is 3MB/512 and at work it's 768/512

Does subsonic re encode at the bitrate i choose for the user or will a 320kb/s mp3 go out at 320kb/s?

by **GJ51** » Mon Jan 10, 2011 9:36 pm

mp3 is what everything gets transcoded to, therefore an mp3 will just get passed to JW Player without being transcoded unless you override the default settings.

Stozher is the one who might be able to tell you how to do that, he's the expert on transcoding.

Does 128kbps tracks play well? The Demo site is all 128kbps mp3, so if you get good performance on the demo site, that's a big clue as to what's going on.

Your 512 upload speed is most likely a factor as that is probably the theoretical speed your ISP tells you you should get. Also, if there is other traffic on the network, it's understandable that a 384 or 320 or even a 256 kbps stream might have issues.

by **pcs800** » Mon Jan 10, 2011 10:13 pm

I suppose I could pm the user you mentioned.

My home network speed being 3meg down and 512 up, I get 3 meg most of the time according to speed tests at dslreports or speakeasy.net

by **GJ51** » Mon Jan 10, 2011 10:31 pm

You can just post the transcoding issue as a new thread as Stozher monitors the forums pretty closely.

I know that speedtests will often confirm your upload speed. The problem comes when you start making several hops over different networks. The data has to go from your server, to a server at your cell provider, and then resent to your phone. There's always some bandwidth loss during the various connections that have to be made. Not only that, your cell provider can have wild fluctuations during a single 3g transmission that range from next to nothing to full rated bandwidth, that may on average look good, but can cause a lot of problems with streaming.

by **pcs800** » Tue Jan 11, 2011 1:05 am

Yeah I am pretty familiar with all that, I'm a network specialist for a local government entity. I wouldn't ask about the server software if I hadn't already tested the network connections between nodes very thoroughly.
Thanks though.

by **GJ51** » Tue Jan 11, 2011 7:50 am

You're welcome to test your phone on my server to determine if the problem is the phone or the server.

http://maplegrove.subsonic.org

usrename&password = guest

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