MPEG-4 Part 2 device specs

[benwaggoner]

So, I'm writing my chapter on encoding for devices.

While H.264 is becoming the "default" it's a real challenge finding a lowest common denominator that works in all devices. In particular, the iPod devices don't support CABAC, and the PSP requires it.

So, it looks like MPEG-4 Part 2 Simple Profile is the lowest common denomiator (iPod and PSP don't support ASP).

Is there a resource somewhere documenting the specifics of what different portable and CE devices handle for MPEG-4 Part 2? The presets in MeGUI don't include anything device specific.

[SeeMoreDigital]

Is there nothing of interest or helpful over on MPEG Industry Forum?

http://www.m4if.org/resources/profiles/index.php

[benwaggoner]

Is there nothing of interest or helpful over on MPEG Industry Forum?

http://www.m4if.org/resources/profiles/index.php
There's tons of interesting and helpful stuff there, but nothing about the specific parameters supported by specific devices.

E.g., what bitrates and resolutions of MPEG-4 Part 2 are supported on the PSP? iPod? All I see in the official support pages is "Simple Profile."

But I bet some devices support at least Simple + B-frames and maybe even quarter pel, even if they don't do GMC or interlaced.

[Dark Shikari]

There's tons of interesting and helpful stuff there, but nothing about the specific parameters supported by specific devices.

E.g., what bitrates and resolutions of MPEG-4 Part 2 are supported on the PSP? iPod? All I see in the official support pages is "Simple Profile."

But I bet some devices support at least Simple + B-frames and maybe even quarter pel, even if they don't do GMC or interlaced.I don't a significant number do qpel, the qpel in ASP was patently insane.

[SeeMoreDigital]

In the days when I had a Sigma Xcard, all of my MPEG-4 encodes were pure simple profile (ie: no custom matrices, no Q-pel, no B-VOP's, no S-VOP's), with AAC audio, aspect ratio signalling and muxed within the .MP4 container.

The only other MPEG-4 SP encoding obstacles I see for individual CE devices are: supported bit-rate, maximum resolution along with audio format and container support... Quite a few then!

[benwaggoner]

In the days when I had a Sigma Xcard, all of my MPEG-4 encodes were pure simple profile (ie: no custom matrices, no Q-pel, no B-VOP's, no S-VOP's), with AAC audio, aspect ratio signalling and muxed within the .MP4 container.
Yeah, I guess that's what's really the baseline for portable device support, then.

Anyone have any good efficiency numbers for SP versus SP + B-frames versus all the ASP features.

I can believe B-frames are worth 20%, but doubt the rest of ASP together would add up to even a 5% improvement on average.

The only theoretically useful tool in there is interlaced, but I can't think of anyone doing interlaced Part 2 these days.

The only other MPEG-4 SP encoding obstacles I see for individual CE devices are: supported bit-rate, maximum resolution along with audio format and container support... Quite a few then!
Exactly the info I'm looking for, and can't find :).

[SeeMoreDigital]

I can believe B-frames are worth 20%, but doubt the rest of ASP together would add up to even a 5% improvement on average.20%... Maybe if multiple B-VOP's were used... But hardware support for multiple B-VOP's is/was an issue. Especially for the .AVI container.

In my opinion S-VOP (GMC) is totally useless. And Q-pel reduces too much background detail for my taste.

The only theoretically useful tool in there is interlaced, but I can't think of anyone doing interlaced Part 2 these days.In my experience interlaced playback was well supported in hardware devices. Support in software players was pants!

Exactly the info I'm looking for, and can't find :).I doubt you will find "definitive" information. The adoption and flexibility of the AVI container (and DivX certification) over the .MP4 container made life difficult for video chip-set and hardware player manufacturers.... Just what do you support? Packed bit-stream for B-VOP's, multiple B-VOP's, Q-pel, 1 warp-point GMC, 3 warp-point GMC! Which audio formats: MP3, AC3, DTS, PCM. Which subtitle formats: SAA, SRT, IDX/SUB etc, etc.

[benwaggoner]

20%... Maybe if multiple B-VOP's were used... But hardware support for multiple B-VOP's is/was an issue. Especially for the .AVI container.
I'd like to apologize for AVI on the behalf of Microsoft :).

In my experience interlaced playback was well supported in hardware devices. Support in software players was pants!
I suppose we should discriminate between battery devices and AC devices. Most of the Divx Certified DVD players did interlaced; is that what you're thinking of?

[SeeMoreDigital]

I'd like to apologize for AVI on the behalf of Microsoft :) Lol.... Joking apart, Microsoft has nothing to apologise for...

I suppose we should discriminate between battery devices and AC devices. With battery CE devices, I suspect most will support resolutions up-to quarter D1 (ie: 352x240/288). But probably top-out at 15fps.

Most of the Divx Certified DVD players did interlaced; is that what you're thinking of?As far as I know, every MPEG-4 video decoding chip-set supporting resolutions up-to D1 was also capable of supporting interlaced MPEG-4.



Cheers

[benwaggoner]

With battery CE devices, I suspect most will support resolutions up-to quarter D1 (ie: 352x240/288). But probably top-out at 15fps.
Really? iPod and Zune both claim to do 30p Simple Profile. iPod up to 640x480 2.5 Mbps, and Zune up to 720x480p30 or 720x576p25 4 Mbps. In an AVI wrapper with MP3 audio no less.

Zune HD will actually do ASP, albeit still limited to SD. It does VC-1 Main and H.264 Baseline+B up to 720p.

Is anyone out there actually using Part 2 on their devices? I'd think the Simple Profile requirement would require a reencode for most stuff anyway, in which case H.264 Baseline or VC-1 Main would offer a lot better compression efficiency.

[SeeMoreDigital]

Really? iPod and Zune both claim to do 30p Simple Profile. iPod up to 640x480 2.5 Mbps, and Zune up to 720x480p30 or 720x576p25 4 Mbps. In an AVI wrapper with MP3 audio no less.

Zune HD will actually do ASP, albeit still limited to SD. It does VC-1 Main and H.264 Baseline+B up to 720p.I see... The info you require is for devices tailored more to media playback. And less-so cell phones... Mind you, even these devices are getting more powerful as their screens get bigger!

[benwaggoner]

I see... The info you require is for devices tailored more to media playback. And less-so cell phones... Mind you, even these devices are getting more powerful as their screens get bigger!
Well, I'm including PMPs as well as phones. Your specs match older phones as well.

Of course, I'm here in the USA where we're a good half decade behind the rest of the world in video-on-phones :). Are people still using and/or encoding for phones with MPEG-4 part 2? I would have thought that H.264 baseline would have hit critical mass by now in Europe and Asia, but that's just speculaton. I could be biased by spending a lot more time reading specs for chipsets yet to ship than specs for the chips people are actually using...