[Ffmpeg-devel] h264 playback performance

[Corey Hickey]

Andreas ?man wrote:
> Hi
> 
> First of all, let me make you understand that the intention of
> this mail is not to whine about the performance of ffmpeg.
> 
> Now, during the summer my tv-provider did some trials with HDTV.
> The video format used was CABAC-encoded h.264 in 720p @ 50Hz running
> at approx 20Mbps.
> 
> Sadly, i discovered that my current machine (Pentium-M w/ 2Mb cache @
> 1.8Ghz) decodes a frame in ~33ms in average (which obviously is too
> slow). I know that the CABAC encoding is quite CPU hungry so it's
> not very surprising.
> 
> I'm about to buy a new machine and I'm interested if anyone with
> a "hot" CPU can try playing the clip I've uploaded and report back.

I can't say for sure with such a short clip, but my system can almost 
handle what you uploaded.

$ mplayer SVT\ HD\ Teaser-ac3-chopped.ts
Triggers the "your system is too slow" message.

$ mplayer SVT\ HD\ Teaser-ac3-chopped.ts -lavdopts skiploopfilter=nonref
A-V desync fluctuates but remains below 0.3 seconds at all times.

$ mplayer SVT\ HD\ Teaser-ac3-chopped.ts -lavdopts skiploopfilter=all
The same as above.

$ mplayer SVT\ HD\ Teaser-ac3-chopped.ts -ao pcm:fast:file=/dev/null \
-vo null -benchmark
BENCHMARKs: VC:   3.815s VO:   0.001s A:   0.064s Sys:   0.059s =    3.939s
BENCHMARK%: VC: 96.8479% VO:  0.0140% A:  1.6306% Sys:  1.5075% = 100.0000%


I have an Athlon64 3400+ Newcastle overclocked to 2.5 GHz.

> Has there been any thoughts about making the h264-decoder
> multithreaded? With the arrival of multi-core CPUs it would
> seem like a wise thing to ponder.

There's '-lavdopts threads=n'. I don't know how well it works, but it 
does run multithreaded.

> I'd be happy to contribute to such a thing, though, it be
> nice to get a few pointers or directions.

If there's anything you can work on, somebody else might be able to give 
you suggestions.

-Corey