FORUMS: list search recent posts

Smartphones video encoding ?

COW Forums : Compression Techniques

<< PREVIOUS   •   VIEW ALL   •   PRINT   •   NEXT >>
Paul Sellis
Smartphones video encoding ?
on Oct 3, 2013 at 5:50:54 pm

Hi,

I am encoding small movies for a web site. I do .mp4 (H264/AAC) with Handbrake.
I need a Web + smartphone audience and I target 480x360px @760kps.

It's OK with WiFi but not on smartphone (HTML5)...
I have tested on iPhone 4 with a 3G connexion: it loads only a few seconds, stops, and so on...
Headache. Not viewable...

Here are my encoding presets 1 and 2
Web optimized is checked, but I don't know if something more need to be specified...

I thought that 760kps should be OK for a standard 3G smartphone connexion. Am I wrong?

Thanks for your advises
Paul


Return to posts index

Craig Seeman
Re: Smartphones video encoding ?
on Oct 3, 2013 at 6:49:38 pm

It might be Profile related although recently iPhones can handle High Profile.
Safest bet for smartphones is to use Baseline profile which would use CAVLC rather than CABAC entropy and not have B-Frames. The reliability of the connection can vary widely also so "3G" is no guarantee of either the speed or reliability of the connection.



Return to posts index

Paul Sellis
Re: Smartphones video encoding ?
on Oct 3, 2013 at 8:28:18 pm

Thank you Craig
I went to Handbrake iPhone presets that uses your settings (no CABAC and no B-Frames) and encoded 2 files:
same thing...

So I think now that the problem should come from somewhere else than from Handbrake:

- as you said the reliability of the 3G connection. I tried 500kps as an alternative but even with such data rate there are problems too. Less but problems...
- the JW Player. But I don't know if the JW Player could be involved as I use it for browsers with Flash but it fallbacks to HTML5 on iPhones. And I think that the HTML5 player is the one included by default in iPhone Safari, so with no JW Player action. Am I right ?
- my mutualized server?... but it's OK with WiFi
- ...


Return to posts index


Craig Seeman
Re: Smartphones video encoding ?
on Oct 3, 2013 at 9:01:20 pm

It depends on the cause of the problem. Handbrake's interface isn't very intuitive. I believe you have make a custom setting to force Baseline profile... assuming that's the problem and it may not be. If it's the profile than fallback may not work. If you try the same file on iPhone 5 or newer and it works it may be a Profile issue as the newer iPhones can play Main and High Profile without issue.



Return to posts index

Paul Sellis
Re: Smartphones video encoding ?
on Oct 3, 2013 at 9:16:45 pm

I don't think that's a High Profile issue as I tried a Handbrake preset "iPhone & iPod Touch" (I use Version 0.9.8). I think that's a Baseline profile, no? (Perhaps I just checked also "Web optimized"). With that preset I should get a file compatible with my iPhone 4. But it's not well played…

The problem should come from something else than a Profile issue.

What do you think?


Return to posts index

Craig Seeman
Re: Smartphones video encoding ?
on Oct 3, 2013 at 9:39:42 pm

Can you send me a link so I can test?
I'm on iPhone 5. I can test both Wifi and LTE (maybe force 3G?) and see what happens.



Return to posts index


Paul Sellis
Re: Smartphones video encoding ?
on Oct 3, 2013 at 9:54:39 pm

Thank you Craig.
You can use this redirection for a while
All the movies have been encoded with my first preset (High profile @ 760kps). Only "Bibi" is an old 500kps file encoded years before with Quicktime or Compressor…
thanks for your discretion as this link has to stay private


Return to posts index

Craig Seeman
Re: Smartphones video encoding ?
on Oct 3, 2013 at 10:13:32 pm

Tested on my iPhone 5 using Wifi (very fast), LTE, 3G
Even though my 3G speed test shows 400kbps down the Déclic video played (looks like slideshow) it just buffered a bit longer.



Return to posts index

Paul Sellis
Re: Smartphones video encoding ?
on Oct 3, 2013 at 10:32:48 pm

Thanks for your patience Craig

The file you played is a slideshow and isn't the perfect one to study problems ! But anyway almost every files have a strobe treatment, so…
;-)


On my iPhone 4 + WiFi I don't have problem. So the High Baseline profile is OK. Anyway you advise me to go to Main profile and I'll go to this more secure way.
There will be quality loss changing to this profile?

You told that with your 3G you get 400kps… It seems desperately low data rate for playing quality video.
What would be your settings to target 3G encodings?

And lastly, I'd like to know what's your iPhone app to test bandwidth. I got "Speedtest.net" but I am not sure that the results are relevant for 3G...


Return to posts index

Craig Seeman
Re: Smartphones video encoding ?
on Oct 3, 2013 at 10:57:27 pm

[Paul Sellis] "So the High Baseline profile is OK. Anyway you advise me to go to Main profile and I'll go to this more secure way.
There will be quality loss changing to this profile?"


Jan Ozer of Streaming Media did a test some months back and he mentioned that some encoders have gotten so get the quality difference between Baseline, Main, High is very small so dropping from High to Main should generally be OK.

[Paul Sellis] "And lastly, I'd like to know what's your iPhone app to test bandwidth. I got "Speedtest.net" but I am not sure that the results are relevant for 3G..."

That's the iPHone app and if you turn off Wifi and LTE and test it'll give a warning but it'll run the test. The low data rate is pretty much what I expected so it seems to be accurate. For 3G I target 500kbps.



Return to posts index

Paul Sellis
Re: Smartphones video encoding ?
on Oct 3, 2013 at 11:05:22 pm

Thanks for all Craig
;-)


Return to posts index

Craig Seeman
Re: Smartphones video encoding ?
on Oct 3, 2013 at 11:10:27 pm

You're welcome of course. :-)



Return to posts index

Paul Sellis
Re: Smartphones video encoding ?
on Oct 4, 2013 at 10:16:08 am

Hmm… Craig I have 2 more questions…
;-)


There's something that I don't understand with 3G speed or reliability of the connection:
how can I have an average 3G connection of 4Mb/s (tests results calculated from time needed to download a 20Mo file) and problems reading a 10Mo file with a 700 or even a 500Kps ? There's something incoherent, no?

(nb: I have downloaded 4Gmark app for iPhone which provides precise tests


Could the High Profile be safely read on all computer?
(only computers, no smartphones nor tablets)


Return to posts index

<< PREVIOUS   •   VIEW ALL   •   PRINT   •   NEXT >>
© 2017 CreativeCOW.net All Rights Reserved
[TOP]