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Advice for best FLV performance

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Mike Lacher
Advice for best FLV performance
on Jan 7, 2009 at 10:26:24 pm

I'm delivering 30sec-2min FLV clips within flash animations for a client. The clips are of talking actors: 15fps, 256kbps, On2 VP6, with alpha channel (they're composited atop interactive backgrounds in Flash). They're preloaded before the user sees them, and they play through NetStream objects. Neither I nor anyone else working on this project has seen any problems in performance, but the client keeps complaining that the video is jerky sometimes.

I'm fairly certain it's just due to watching it on slower computers, but they're adamant about fixing it. I've tried numerous things which have led to the current settings, the best so far. I've tried ditching the alpha channel and comping in the background in the video, but it didn't help (it seemed worse to them. sigh...).

Does anybody have more ideas about how to make the FLVs perform better? I'd appreciate any ideas.

Thanks,

Mike


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Daniel Low
Re: Advice for best FLV performance
on Jan 7, 2009 at 11:19:33 pm

You're probably right about the performance of the clients computer, you need to check how old it is.

If it's newish, check they don't have a gazillion applications running on it/limited RAM/or usual corporate firewall/anitvirus junk overloading it.

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Kris Anderson
Re: Advice for best FLV performance
on Jan 8, 2009 at 12:31:03 am

Is it possible that the 'jerkiness' is due to the 15fps? Maybe try a 30fps version and see what they say.


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Daniel Low
Re: Advice for best FLV performance
on Jan 8, 2009 at 12:45:30 am

Actually, pretty well most of it looks like 24 (23.98) fps, there are some slo-mos, but they look like they are rather well interpolated or shot fast in the first place.

Nothing looks 15fps when played locally on my very ancient test Mac.



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Mike Lacher
Re: Advice for best FLV performance
on Jan 8, 2009 at 3:25:37 pm

Thanks for the feedback.

Whenever I ask for tech specs of their machines, I just end up with more demands. They're of the belief that this should run on every computer ever made. I'm positive it's due to a slow machine. I'm just looking for any possible way to make it play a little better.

I don't think it's the 15fps thing. I suspected that at first too, but the clients say the beginning parts of some videos appear jerky then are fine. Many videos they think work fine. It's just the long ones that tend to have "jerky" part.

Daniel, I didn't quite get the last post. What video were you referring to in terms of it looking 24fps?

Am I correct in thinking that going with h.264 wouldn't improve performance (I'd have to comp in all the backgrounds)? I haven't dealt with the format much in Flash, but from what I understand it's more CPU intensive than VP6.

Thanks again for everybody's help.

-Mike



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Daniel Low
Re: Advice for best FLV performance
on Jan 8, 2009 at 3:35:24 pm

Sounds like a typical client to me!

I'm so sorry, I got this post mixed up with another post that's having similar jerkiness problems with a flash video!

Anyway, one way to improve performance is to pre-comp everything. Compositing at the player end is too much of a CPU hog.

H.264 will be even harder for a low-end PC to play back

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Mike Lacher
Re: Advice for best FLV performance
on Jan 8, 2009 at 3:40:26 pm

No problem. I figured something got mixed up.

Sadly, I already tried pre-comping some videos and of course the client tested and complained that the pre-comped ones were still jerky and the un-comped ones looked fine (heavy sigh).

Any other thoughts on optimization? I know I'm running out of options...



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Daniel Low
Re: Advice for best FLV performance
on Jan 8, 2009 at 3:49:27 pm

Any chance of seeing an example of one?

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Mike Lacher
Re: Advice for best FLV performance
on Jan 8, 2009 at 4:07:06 pm

I wish. It would make things much easier. Unfortunately, it's totally covered by non-disclosure, so my putting piece of it online would result in a large amount of trouble.

The most detail on the videos I can give you is in terms of metadata, which I know is much less helpful than the genuine artifact. Also, I don't know if I mentioned this, but the client generally experiences the most problems in the first 10 seconds of longer videos (over 1.5 min).



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Daniel Low
Re: Advice for best FLV performance
on Jan 8, 2009 at 4:20:35 pm

Ok, fair enough.

Please then give a complete breakdown of your encoding settings:

Frame size
Keyframe rate
Audio data rate
Etc

If this problem happens in the first 10 seconds this can be the result of hiccups as the movie has finished progressively downloading. Ask them to visit a number of other sites and see what they experience. eg.hulu.com, youtube, vimeo etc


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Mike Lacher
Re: Advice for best FLV performance
on Jan 8, 2009 at 5:31:25 pm

Here's the info. Thanks for helping with my rather ambiguous and hopeless quest.

Frame size: 776x504 (this varies somewhat. this size is for one of the more problematic videos)
Duration: 65s
Audio codec: MP3
Audio codec ID: 2
Audio datarate: 32kbps
Video codec: On2 VP6
Video codec ID: 4
Video datarate: 224kbps
Framerate: 15fps
Keframes: I had this set to auto when exporting from AE. It looks like AE made them every 2-4sec

And it has problems with or without alpha channel.

It should be completely done loading by the time the video plays. In all the tests I've done, the preloading has worked. I'm building a test now for the client to definitively make sure that it's preloading for them.

Thanks again,

Mike



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Daniel Low
Re: Advice for best FLV performance
on Jan 8, 2009 at 6:26:03 pm

that's a huge frame size for the given datarate and also neither 4:3 or 16:9? Are you using AE to do your encoding? It's ok for casual stuff but nowhere near good enough for client ready work.

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Mike Lacher
Re: Advice for best FLV performance
on Jan 8, 2009 at 7:05:28 pm

The frame size is big so the characters fit the background and the data rate is so low because I had to bring it down for slower connections. Quite a bit of compromise, as I'm all too painfully aware. It's not 4:3 or 16:9 because it's keyed DVCPRO HD footage cropped to the minimum size needed.

I admit a large amount of ignorance when it comes to compression software. I've always just used AE because it's what I have. Is there stuff you recommend or somewhere good to look to learn more? I doubt it'll be an option for this project at this stage in the game, but I'd be interested to learn more. Would using better software help with performance, or would it mainly help with appearance?

Continued thanks,

Mike



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Daniel Low
Re: Advice for best FLV performance
on Jan 8, 2009 at 7:24:47 pm

Flash video works best at certain frame sizes. It's best therefore to stick to defined aspect ratios and frame sizes equally divisible by 8 or 16 on both axis.

You will almost certainly get better results using a dedicated encoding application. I'd recommend Episode from Telestream but there are other on both platforms ranging from free to very expensive that can probably do a better job than AE.

Ultimately - I'd reduce the frame size as I'm sure your client will see less of the problems. You can't compromise too much without messing everything up, something has to give and in your case it's playback performance.




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Mike Lacher
Re: Advice for best FLV performance
on Jan 8, 2009 at 7:38:16 pm

Thank you. That's really interesting about frame size. I'm going to try changing that and see what happens. Also going to look into getting my office to buy compression software. The more I read, it seems like an obvious advantage over AE.

Do you mind me asking (and I realize you've already given me plenty of your time) what free programs you're talking about that encode better than AE?

Continued continued thanks,

Mike



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Daniel Low
Re: Advice for best FLV performance
on Jan 9, 2009 at 10:44:29 am

Mac or PC?

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Mike Lacher
Re: Advice for best FLV performance
on Jan 9, 2009 at 3:00:23 pm

PC.

I changed some videos from their strange dimensions to 16:9, and they actually look better. Thanks for the advice. I would have never thought of it. Still waiting to hear if it has any effect on the client's end.

Also starting to play around with a trial of Episode. I have a lot to learn...



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Rich Rubasch
Re: Advice for best FLV performance
on Jan 10, 2009 at 12:57:27 am

In your original post you said the videos preload before the client sees them, but the problem playback in the first 10 seconds indicates that there is a load problem. Is the buffering set for a particular duration of time or the entire clip?

Could make the buffer time longer.

I agree that frame size is a critical component of smooth playback. Ask the client to preview some smaller frame sizes and see how small they will go, then slim down your bitrate in small bites until it plays smooth for them. You are really at the bottom end of the bitrate scale however.

My DSL connection at my home always chokes on flash videos. I am getting about 175 kbps download here at the end of the DSL line in my home. They are telling me it is a 512 kbps service!

Good luck,

Rich Rubasch
Tilt Media



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Mike Lacher
Re: Advice for best FLV performance
on Jan 12, 2009 at 3:35:51 pm

The videos are fully preloaded before they start, so I can't do much in terms of buffer. I just ran tests and they're definitely loading all the way before playing.

And sadly I don't have much wiggle room with frame size at this point. They like how it looks and I'd have to redo interactivity and backgrounds and everything. It's certainly something I'll keep in mind for the future though so hopefully i can avoid this happening again.

The good news is, changing the frame size to 16:9 instead of the non-standard size i had seems to be making a difference. They haven't been having any playback issues. This could also be a fluke, since this problem doesn't happen consistently for the client. I'll have to wait and see if further problems arise. I finally got specs from them any they're running it on a machine with a centrino duo processor and 2gb RAM, which seems more than enough to handle low-datarate FLVs. Maybe it's some bizarre glitch with frame dimensions.

Thanks again to everyone for their help,

Mike



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Mike Lacher
Re: Advice for best FLV performance
on Jan 19, 2009 at 10:03:52 pm

Just for the benefit of anybody reading this at a later junction, it turns out resizing the videos to standard aspect ratios worked. I made all the videos 4:3 or 16:9 and they're now working great for the client.

I'm still not sure why exactly they had performance issues. They were running it on a dual-core centrino with 2gb ram, which seems beefy enough for low-datarate FLVs. It also turned out that no one in the user test reported problems (which of course the client decided not to tell us for some time).

Anyway, much thanks to Daniel. I would have never thought to change the aspect ratio to improve performance. I really really really appreciate it. You've saved me and my coworkers from added weeks of drama.

Thanks again,

Mike



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Daniel Low
Re: Advice for best FLV performance
on Jan 19, 2009 at 11:21:24 pm

Mike,

Thanks for letting us know.


Daniel.

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