[vlc] Re: HDTV Transport Streams (.ts) and Performance

[Galen]

On Dec 3, 2004, at 11:46 PM, Benjamin PRACHT wrote:
> Well, HDTV streams have always required quite a big CPU for decoding,
> and I've never seen such a stream played fine on a G4... I don't think
> recompiling VLC will help (all the available optimisations of VLC are
> already included in the standard binaries). VLC uses limpeg2 for mpeg2
> decoding, which is considered as a fairly efficient mpeg2 decoder, and
> include some altivec optimisations as well. On the other hand, there
> is certainly still some room for optimisation in VLC's code (debugging
> the OpenGL vout would be a start), but this would require some time and
> skills, and I'm not sure even would allow playback of HDTV streams on a
> G4

I wasn't thinking of recompilation alone, more along the lines of 
changing things then recompiling. I couldn't imagine that I would gain 
much, if anything, assuming that the people doing the default VLC 
builds were clueless, considering the performance intensive-nature of 
video playback. But recompiling would let me tweak things around a 
bunch in the source code.

Is there any way to take decoding shortcuts here? Note that I only need 
1280 x 720 pixels of video (any more would exceed the size of my 
display) - is there perhaps something that could help here? (I remember 
back in the days of QuickTime when codecs would play smoothly at half 
size but not at full size)

I'm also wondering if shortcuts could be taken to reduce the CPU used 
in the decoding process - even if they compromise quality. I doubt a 
slight compromise in quality would be a problem, considering that the 
video will be scaled down to be able to fit on my display.

Is there anything else - the buggy OpenGL stuff perhaps - that would 
accelerate playback?

Ideas anybody?

> . BTW, such streams play fine on G5 cpus...

Sounds like a plan! I'll let you figure out how to cram a G5 into a 
laptop that doesn't fry my lap, and I'll go for it! :)

Until then, this computer is pretty much as fast as Mac laptops come. A 
laptop is the only viable option for me at the moment, so although a G5 
would be great, it simply would sit unused most of the time. Although 
watching 1080i HDTV on a 30" display does have it's appeal...

-Galen

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