4.3 Beta and M-720p mp4's buffering every 10 seconds

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4.3 Beta and M-720p mp4's buffering every 10 seconds

Postby ritalin » Tue Jan 04, 2011 9:56 pm

Overall the video streaming is working very well out of the box with no adjustments to the transcoding. I am having some issues with about 30 or so of my videos that are all mp4 and m4v files with a resolution of 720p and an overall average bitrate of around 1027kbps. All of the videos at or around this spec buffer ever 10-15 seconds be it over 3g or Wifi.

I am not really sure of how to go about editing the transcode to get a smoother playback experience. As stated at present the transcode settings are at default.

MP4 Step 1
ffmpeg -ss %o -i %s -b %bk -s %wx%h -ar 44100 -ac 2 -v 0 -f flv -


If anyone could offer a hand Id greatly appreciate it.
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Postby GJ51 » Tue Jan 04, 2011 10:09 pm

MP4 files will play directly to JW Player without transcoding on the desktop browser. Just uncheck the box in the settings for the player you use on your desktop browser, and the MP4's should play without any problems.

I haven't done any work with an M4v file yet so i don't know if there's an easy fix there.
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Postby ritalin » Tue Jan 04, 2011 10:22 pm

GJ51 wrote:MP4 files will play directly to JW Player without transcoding on the desktop browser. Just uncheck the box in the settings for the player you use on your desktop browser, and the MP4's should play without any problems.

I haven't done any work with an M4v file yet so i don't know if there's an easy fix there.


Im sorry but I should have stated that this is for my Android phone, a Galaxy S Vibrant.
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Postby GJ51 » Tue Jan 04, 2011 11:00 pm

http://forum.subsonic.org/forum/viewtop ... ght=#19128

It's pretty much dependent on connection speed and how fast your server can serve up the data. Classic weakest link theory. For videos over 3g I think the best results will be to convert files to lower resolution flv files first, for playback on the phones. 3G connection speeds are notoriously erratic and don't always correlate to how many bars your phone shows. I can play most video on my EVO over Wifi with the default settings, but on 3G i usually have to select the 200 kbps setting on the player to get continuous playback, even with a pretty good 3G signal. Your phone's graphocs playback power can also be a factor. Remember, you probably won't get any better results with your phone than you do with a You Tube clip, assuming that you have as much upload speed as You Tube.

I'm overall pleased with the playback capability on my EVO. This afternoon, while waiting to pick up my kids from school, I watched part of "Stargate", the original movie that was ripped from DVD to MP4 on my EVO using the 200kbps setting on the Android app player. Playback was smooth and never paused or skipped.

Having a good sense of what the limiting factors are goes a long way in helping to get reasonable results that are possible with your unique hardware configuration. Once you get a feel for your options, you can then start to develop a good strategy for setting up your video files in formats and folders that work the best for the target device you want to use for viewing.
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Postby ritalin » Wed Jan 05, 2011 12:31 am

GJ51 wrote:http://forum.subsonic.org/forum/viewtopic.php?p=19128&highlight=#19128
Having a good sense of what the limiting factors are goes a long way in helping to get reasonable results that are possible with your unique hardware configuration. Once you get a feel for your options, you can then start to develop a good strategy for setting up your video files in formats and folders that work the best for the target device you want to use for viewing.


Well Im sitting on the same FIOS connection you are 35/35 with an average of about 25up. So I know its not my upload bandwidth. The buffer is still present when I am at home over wifi on my phone, so there is something besides bandwidth at play here, or so it would seem.

Are you using the same settings I have listed above for MP4/M4V? The other question is wouldnt the increased resolution cause some sort of issue? I am talking about a low bitrate 720p and you are talking about an even lower bitrate SD/480p file.

Is there a way to force higher resolution files to transcode to a smaller resolution or does it do this automatically?

Thank you for your help so far, by the way.
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Postby GJ51 » Wed Jan 05, 2011 5:21 am

You should definitely be able to get better results. The problem is finding out where the bottleneck is. I'm able to watch ripped standard DVD quality video over 3G to my EVO when I get a good signal. So let's look at the chain to see if we can find a weak link. The server is where it all starts. Does your server transcode on the fly fast enough to feed the data stream? How did you test it to see if that's an issue? Next, what's the speed of the pipe? Are you on gigabit lan, wireless N, have you tested throughputbetween devices? The phone, usually the weak link, have you run a speedtest to see what kind of data transfer you're getting.

I've got a quad core Xeon 3.0 Ghz CPU with 8GB of ram in my server, but in testing I found that ffmpeg only uses one core per video stream for transcoding. It seems to be enough most of the time, but squeezing a HD Bliue Ray quality mp4 down to a 200kbps video for the Android player maxes out the core the transcoding is being done on. That said you should still be able to find a good combination that works well on your phone, especially if your connecting over wireless N.

The default seup allows you to select the transcoding bitrate from the player creen in the Android app.

ffmpeg -ss %o -i %s -b %bk -s %wx%h -ar 44100 -ac 2 -v 0 -f flv -

These are the setting I'm currently using. The default 500 Kbps works fine over Wifi with anything but Blue ray quality video. At highest qualtiy HD the player will start buffering after a bit and becomes annoying. Anything else plays start to finish, no problems. Again, this is on an EVO 4G phone which has a pretty good CPU and graphics capability for a cell phone. A different phone may have trouble handling the same data stream. I'm also not sure if empty space on the SD card is a factor or not, but if were having problems, that's one thing I would look at.

You can test your phone on my public server at maplegrove.subsonic.org using guest for username and password if you like. There are some videos in the video folder. The Dvorak Concert is a recording of my son's Orchestra when they played in Prague at Dvorak Hall last summer. Boring unless you're into classical music, but a good test to see if your phone can play it over Wifi. It's 734kbps. It should play well at 500 set on the player but need to be turned down to 200 or 300 kbps to play without pauses over a good 3g signal.
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