Freezing problem with FLV video

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Aug. 19, 2008Simon Houghton

Hi there.
I'm a complete novice to all this putting flash movies onto the web, but I have managed to do it, using the latest JW Flash player, and converted a WMV file to FLV using Moyea Video4Web (Windows).

When the clip plays, it SOMETIMES freezes, and I can't get beyond that point. If I press F5, it sometimes works, in that the file plays fine. I have run the FLV file created, locally from my PC, and it works fine. So something is not right from when it is hosted on the site. I don't really want to have to put a message up on the site saying "if you experience problems, try pressing F5" etc...!

If anyone has the time to look at the code in www.mindfocusforgolf.com/demo/index.html, I would be very grateful. I'm not a technical person, so be gentle!
Many thanks,
Simon.

Aug. 19, 2008kLink

Some recommendations:

1) Get FLVMDI (Google for it) and use it to inject the metadata array into your video after you have encoded it.

2) Your server is having a hard time delivering the video as fast as it is consumed; that is probably the main reason for the stalls. As soon as some more video is buffered, playing resumes. Consider encoding at a lower bitrate. Your video is encoded at 1048kbps which is quite high for Internet video. 600-800kbps is probably sufficient.

3) Size the display area of your player to be the same size as your video's native size (360x252). This will reduce the load on the client CPU because Flash burns a lot of CPU cycles re-sizing on the client.

var s1 = new SWFObject('http://www.mindfocusforgolf.com/flashplayer/player.swf','player','360','272','9');

The height is 252 + 20 for the control bar.

4) Consider reducing the keyframe interval. Right now your video has keyframes every 0.48 seconds. That enables you to scrub in 0.48 second intervals, but greatly increases the size of the video file. Usually keyframes every 2 to 3 seconds is sufficient for scrubbing.

5) Consider reducing the framerate from 25fps to 20fps. I doubt you will see much reduction in quality and again, this will greatly reduce the data transfer rate.

Aug. 20, 2008Simon Houghton

Brilliant - thanks so much.
I have reduced the framerate, bitrate, and the display area, and this seems to have sorted the problem.
If you have the opportunity to answer 3 questions based on the information you supplied, it will help me for future videos!
1. How do I change the keyframe interval - it wasn't available on Moyea, so is this something I need to address?
2. How do you determine the size of the video's native file size - is there an easy way to do this? When converting, the option is to keep original size, so I don't know what size it was, but obviously there's a way, because you told me the dimension!
3. FLVMDI - I haven't done this yet - what exactly will it do for me, and what do I actually have to do/provide when it is run - is it a 'press and play', or do I have to provide information (bit rate, etc.)

Thanks very much for helping me to do this - much appreciated.
Simon.

Aug. 20, 2008kLink

The keyframe interval may be called something else, like group of pictures, or something to do with scrubbing, depends on the encoding software. But there definitely should be a way to set it. According to the Moyea forums here: http://www.moyea.com/forum/ it is called "frames between keyframes"

I determined the size by looking at the xml file that FLVMDI generated when I used the /x switch.

FLVMDI is a command line program.
Normal FLVMDI usage is: FLVMDI /k video.flv
To generate the xml: FLVMDI /k /x video.flv

FLVMDI creates and injects the metadata array into the FLV container. It only needs to be run once after you finish encoding the FLV. The main purpose is to inject the time/position metadata that the JW FLV Media Player needs for scrubbing to keyframes.

Aug. 20, 2008Simon Houghton

Brilliant!
Thanks very much - you've been really helpful.

Simon.

Aug. 20, 2008kLink

@Simon,

You're welcome, I hope you enjoy your new toy!

Nov. 17, 2008Matt

Hi there,
I have a similar problem in that the flash movie freezes after the 4th or 5th load.
Initially put it down to mime types which was modified according to kb: http://kb.adobe.com/selfservice/viewContent.do?externalId=tn_19439. After a server restart it did not resolve the issue.

steps to reproduce:
Open IE 7.0
go to: http://www.essa.com.au/EssaProductsDefault.aspx?MenuID=110
click on any video. a new window will popup.
It will most likely play ok for the first 3 or 4 times. close the window.
keep opening until it freezes (or just thinks and eventually times out).

The initial problem may of been the mime type however, there may be something else amiss. Some videos are 10mb otheres are 80mb. It happens no matter what size.

Any advice appreciated.

Nov. 17, 2008kLink

It's the IE "cache feature". Google for more.

Nov. 18, 2008Matt

Thanks for the tip. I did google but could find nothing obvious? Found this post http://support.microsoft.com/kb/234067 and added the meta tags but did not resolve.

Nov. 18, 2008kLink

The Google tip was mostly meant for information only. You can implement a "cache buster", but that means that the media files will be downloaded for each play.

The common "cache buster" is to append a random number on to the file URI. In fact, you will see that this has already been implemented for playlists, so you get a fresh playlist on every reload. Look in your server logs, you will see: "GET /path/playlist.xml?123...".

Googling "Internet Explorer cache buster" you will see that there are many serverside/clientside techniques to prevent this behavior, although they all result in the media files being downloaded again and again. Without "cache busting", I've seen IE take up to a full minute to look through it's cache before it starts loading the cached file.

Nov. 03, 2009Barrie Blackmore

I own a video production company, and have been producing videos for the web since 2002 using aJava script which has the player build into it.

We encode for 6 bandwidths from 56k modems to high end broadband. and evry video stram plays for hours with no freezing at all.

The problem with flash video is the fact that the file size is to big for the UK's broadband infrasructure.

Our Clipstream Java Software encodes the video at half the file size of flash, and enables a viewing of 98.9% a viewing world wide, we can also produce chapters as well and plays on any bandwidth a person has at any given time.

The Java Clipstream Software, is worth ever penny, it gets the video message across with no freezing and plays instantley.

Please contact us for further information on how to provide your customers with none stop video streaming at a stroke, with excelent quality.

Check our web site www.adv2021multimedia.com or www.equsterlink.com

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