pmts
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Re: Video decoding specs?

Tue Apr 10, 2012 8:00 pm

Hi,

I've been googling for this for half an hour now and can't find it. What are the specs of the hardware h264 decoder? What is the max level / bitrate? Are there limits on the number of B frames or something like that? Could it play a blu-ray disc (in terms of video decoding capability only)?

Also, what API does it use? VAAPI? VDPAU?

fakeplastic
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Re: Video decoding specs?

Tue Apr 10, 2012 8:31 pm

I think you can find what your looking for here:

http://elinux.org/RPi_Hardware

honda4life
Posts: 75
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Re: Video decoding specs?

Tue Apr 10, 2012 8:32 pm

I personally think...

Video decoding specs isn't the only important thing.

I assume you wach a movie/BD,... with sound so what about sound decoding?

AC3, DTS???

Many people think wow running XMBC on a 35 dollar computer, I must have one.

... many will be dissapointed. (the percentage of XMBC related orders is high I think).

Don't understand me wrong, the porting of XMBC to RPi is awesome but it's just the interface and not the multi format support and not the smooth playback.

pmts
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Re: Video decoding specs?

Tue Apr 10, 2012 8:44 pm

fakeplastic said:


I think you can find what your looking for here:

http://elinux.org/RPi_Hardware


Nope, nothing there. Only "1080p30 H.264 high-profile decode", which is the same as everywhere else and very vague.

honda4life said:


I personally think...

Video decoding specs isn't the only important thing.

I assume you wach a movie/BD,... with sound so what about sound decoding?

AC3, DTS???

Many people think wow running XMBC on a 35 dollar computer, I must have one.

... many will be dissapointed. (the percentage of XMBC related orders is high I think).

Don't understand me wrong, the porting of XMBC to RPi is awesome but it's just the interface and not the multi format support and not the smooth playback.


I know there's much more to it. I only wanted a general idea of the decoding power, that's why I wrote "in terms of video decoding capability only".

On the other hand, decoding 448k ac3 track shouldn't be too taxing to the CPU. Right?

jamesh
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Re: Video decoding specs?

Tue Apr 10, 2012 9:00 pm

pmts said:


Hi,

I've been googling for this for half an hour now and can't find it. What are the specs of the hardware h264 decoder? What is the max level / bitrate? Are there limits on the number of B frames or something like that? Could it play a blu-ray disc (in terms of video decoding capability only)?

Also, what API does it use? VAAPI? VDPAU?


About 50MBits/s max. Not sure what you mean by B-frame limit.  Yes, it can play a Bluray spec file.  Think it's High profile level 4.1 from memory.

API is a custom Broadcom one. A player app is included in the distro's.

Although the GPU can easily decode audio of whatever you want, licences are too expensive, so you need to do it on the Arm. Dolby DTS 7.1 takes about half the available CPU power, if I remember a post from Dom correctly.
Principal Software Engineer at Raspberry Pi Ltd.
Working in the Applications Team.

pmts
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Re: Video decoding specs?

Tue Apr 10, 2012 9:06 pm

That's what I wanted to know. Thanks!

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reiuyi
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Re: Video decoding specs?

Tue Apr 10, 2012 9:07 pm

"high profile" is a standard. If you encode high profile 1080p the gpu will play it. I think it was mentioned once the gpu has upto "level 4" h264 support.  You can ask wikipedia to what bitrate that equates.

The BCM2835 contains the same h264 hardware decoder as the BCM970012, I suspect. I have one of those in my laptop and it hardware-decodes absolutely every piece of junk h264 I can find.

If you're wondering about youtube, hulu, anime, piratebay films, etc; it will play all of these just fine. If it contains mp3/aac/flac audio there really shouldn't be any issue. If you're wishing to hear information regarding subtitles; you'll be disappointed how CPU-intense some of the fancy anime subs can be. Especially karaoke stuff (softsubs) will not work at all. Regular white-text ones will not be an issue. The CPU can decode audio just fine it's a pentium 3

pmts
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Re: Video decoding specs?

Tue Apr 10, 2012 9:14 pm

DeliciousRaspberryCake said:


"high profile" is a standard. If you encode high profile 1080p the gpu will play it. I think it was mentioned once the gpu has upto "level 4" h264 support.  You can ask wikipedia to what bitrate that equates.


"High profile" is just a set of features, it doesn't say anything about bitrate. There are "Levels" that define max bitrate: http://en.wikipedia.org/wiki/H264#Levels . As JamesH wrote, RP decodes up to Level 4.1.


The BCM2835 contains the same h264 hardware decoder as the BCM970012, I suspect. I have one of those in my laptop and it hardware-decodes absolutely every piece of junk h264 I can find.

If you're wondering about youtube, hulu, anime, piratebay films, etc; it will play all of these just fine. If it contains mp3/aac/flac audio there really shouldn't be any issue. If you're wishing to hear information regarding subtitles; you'll be disappointed how CPU-intense some of the fancy anime subs can be. Especially karaoke stuff (softsubs) will not work at all. Regular white-text ones will not be an issue.


Thanks, that's good to know.


The CPU can decode audio just fine it's a pentium 3


wat

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jbeale
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Re: Video decoding specs?

Tue Apr 10, 2012 9:51 pm

"...Overall real world performance is something like a 300MHz Pentium 2, only with much, much swankier graphics." -http://www.raspberrypi.org/faqs

pmts
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Re: Video decoding specs?

Tue Apr 10, 2012 9:53 pm

jbeale said:


"...Overall real world performance is something like a 300MHz Pentium 2, only with much, much swankier graphics." -http://www.raspberrypi.org/faqs


Thanks, I always wondered how ARM compares to x86s

JeremyF
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Re: Video decoding specs?

Tue Apr 10, 2012 10:23 pm

jbeale said:


"...Overall real world performance is something like a 300MHz Pentium 2, only with much, much swankier graphics." -http://www.raspberrypi.org/faqs



I never quite understood that statement. Is it like a Pentium II running Windows 98 (i.e. perfectly fine) or is it like a Pentium II attempting to run Windows XP? Because while the hypothetical Pentium II might be running the running the same speed in both situations, it's going to feel slower on a hypothetical Windows XP.
{sig} Setup: Original version Raspberry Pi (B, rev1, 256MB), Dell 2001FP monitor (1600x1200), 8GB Class 4 SD Card with Raspbian and XBMC, DD-WRT wireless bridge

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reiuyi
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Re: Video decoding specs?

Tue Apr 10, 2012 10:26 pm

pmts said:


"High profile" is just a set of features, it doesn't say anything about bitrate. There are "Levels" that define max bitrate: http://en.wikipedia.org/wiki/H264#Levels . As JamesH wrote, RP decodes up to Level 4.1.


There's one thing I must add apart from Jamesh's post;  levels don't say much about the maximum profile. The iPod touch might be level 3.1, but It will never ever play high-profile. This has to do with the complexity of CABAC/CAVLC which I don't even know what they are but they increase quality while retaining bitrate

Though my post doesn't add much; the discussion was already resolved , broadcom has some fine hardware decoding and I'd love to see it being implemented properly because bcm970012 is really really badly supported by Flash under Windows. I think someone in the Foundation actually designed that chip, so I better stop down-talking it because it's a miracle chip when the drivers and Flash work in harmony

pmts
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Re: Video decoding specs?

Tue Apr 10, 2012 10:30 pm

DeliciousRaspberryCake said:


pmts said:


"High profile" is just a set of features, it doesn't say anything about bitrate. There are "Levels" that define max bitrate: http://en.wikipedia.org/wiki/H264#Levels . As JamesH wrote, RP decodes up to Level 4.1.


There's one thing I must add apart from Jamesh's post;  levels don't say much about the maximum profile. The iPod touch might be level 3.1, but It will never ever play high-profile. This has to do with the complexity of CABAC/CAVLC which I don't even know what they are but they increase quality while retaining bitrate



Yes, that's what I was saying. "High profile, level 4.1" tells me all I want to know.

jamesh
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Re: Video decoding specs?

Wed Apr 11, 2012 8:14 am

DeliciousRaspberryCake said:


pmts said:


"High profile" is just a set of features, it doesn't say anything about bitrate. There are "Levels" that define max bitrate: http://en.wikipedia.org/wiki/H264#Levels . As JamesH wrote, RP decodes up to Level 4.1.


There's one thing I must add apart from Jamesh's post;  levels don't say much about the maximum profile. The iPod touch might be level 3.1, but It will never ever play high-profile. This has to do with the complexity of CABAC/CAVLC which I don't even know what they are but they increase quality while retaining bitrate

Though my post doesn't add much; the discussion was already resolved , broadcom has some fine hardware decoding and I'd love to see it being implemented properly because bcm970012 is really really badly supported by Flash under Windows. I think someone in the Foundation actually designed that chip, so I better stop down-talking it because it's a miracle chip when the drivers and Flash work in harmony


Don't blame us for Flash's shortcomings! Adding video acceleration to Flash needs to be done by someone by modifying the Flash code itself.
Principal Software Engineer at Raspberry Pi Ltd.
Working in the Applications Team.

bbramble
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Re: Video decoding specs?

Wed Apr 11, 2012 9:00 am

JeremyF said:

I never quite understood that statement. Is it like a Pentium II running Windows 98 (i.e. perfectly fine) or is it like a Pentium II attempting to run Windows XP? Because while the hypothetical Pentium II might be running the running the same speed in both situations, it's going to feel slower on a hypothetical Windows XP.
It's quite simple. The R-Pi has roughly the performance of a Pentium 2 @ 300MHz.

The OS is completely irrelevant to the processor performance, not just because your given examples won't run on the R-Pi so no comparison can be made. The subjective speed of an OS that may not run well on a particular processor is not usually considered a sensible benchmark.

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hayesey
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Re: Video decoding specs?

Wed Apr 11, 2012 9:20 am

JeremyF said:


I never quite understood that statement. Is it like a Pentium II running Windows 98 (i.e. perfectly fine) or is it like a Pentium II attempting to run Windows XP? Because while the hypothetical Pentium II might be running the running the same speed in both situations, it's going to feel slower on a hypothetical Windows XP.


well it's like a Pentium II running whatever software you choose to run on it.  If you were to somehow get hold of a copy of Windows 98 compiled for ARMv6 then yes it'll run like that.

It should handle a well configured Linux system with a lightweight desktop OK.  But it all really depends what software you are to use.

But the statement that the hardware itself performs like a PII 300MHz is still valid.  But that's only when the GPU isn't being used, for code being executed on the GPU, performance is much better than you'd ever get from a single PII 300Mhz system.

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