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Here are my Mplayer benchmark results for .webm file (1792x1080):

PowerMac G5 "Quad": 443,328 s
PowerMac G5 "DP" 2,7 GHz: 545,702 s
iMac G5: 575,818 s
PowerBook G4 1,67 GHz: 709,675 s
iBook G4 1,33 GHz: 864,667 s

what is more interesting, for a mp4 file (1280x544) results are:

PowerMac G5 "Quad": 14,023 s
PowerMac G5 "DP" 2,7 GHz: 24,108 s
iMac G5: 19,256 s
PowerBook G4 1,67 GHz: 36,631 s
iBook G4 1,33 GHz: 43,699 s

so a big advantage for the PCIe models over the AGP equipped G5.

> Here are my Mplayer benchmark results for .webm file (1792x1080): [...]
> what is more interesting, for a mp4 file (1280x544) results are: [...]
> so a big advantage for the PCIe models over the AGP equipped G5.

Per-clock performance (higher = better) normalized to "1.00 = slowest" is this:

webm | mp4
1.33 | 1.86 : PowerMac G5 "Quad"
1.00 | 1.00 : PowerMac G5 "DP"
1.22 | 1.61 : iMac G5
1.25 | 1.07 : PowerBook G4
1.28 | 1.12 : iBook G4

(I hope I correctly assume that the video files were read from the RAM disk in any case, so that storage connection speed plays no role.)

Your observation is certainly correct as in both tests, the slowest is the AGP G5 and the fastest is one of the PCIe G5s, so among the G5s the type of GPU connection seems to be the determining factor for video playing performance.
Regarding G4 vs. G5, it can be seen that the G4s are found between the two PCIe G5s for high-res WebM video replay, and that the G4s are found between the AGP G5 and the PCIe G5 (but just above the AGP G5) for low-res MP4 video replay. I'd say that there can't be a unidimensional explanation for these G4 vs. G5 per-clock performance results. It's rather that these mixed results stem from factors like SIMD performance, memory bandwidth and microarchitectural code tuning interfering with each other.

Thanks for sharing your mplayer benchmark results!

AFAIK the PCIe models also got DDR2 RAM vs. DDR1 RAM in the AGP models. Would be interesting if a PowerBook G4 5,8 is faster than a 5,6 one. Both clock at 1,67 GHz but the former has DDR2 RAM.

My MPlayer benchmarks were made on a "DDR2" PowerBook. I don't have a 5,6 at hand but I know a guy that's got one. I'll try to contact him and we'll see if the memory type has any meaning here.

> AFAIK the PCIe models also got DDR2 RAM vs. DDR1 RAM
> in the AGP models.

Correct. It would be interesting to know whether the MPlayer performance advantage of PCIe/DDR2 G5 over AGP/DDR1 G5 is caused by the faster GPU connection like we've assumed in this thread, or by the (theoretical) doubling of the memory data transfers per clock cycle, or a combination of both.

> Would be interesting if a PowerBook G4 5,8 is faster than a 5,6 one.
> Both clock at 1,67 GHz but the former has DDR2 RAM.

The G4 CPU can only transfer data on one edge of the bus clock signal, so it utilizes DDR1/DDR2 memory as if it was SDR memory. The doubling of the theoretical data rate from SDR to DDR1 and again to DDR2 is completely lost on the G4 CPU. The memory controller of G4 Macs with DDR1/DDR2 memory however is able to transfer data on both edges, so controllers connected to the northbridge may be served on both edges, but the CPU itself cannot.
Also, you can see with koszer's lame_vmx and MPlayer results that the per-clock performance of the iBook with DDR1 is actually higher (single-digit percentage) than that of the PowerBook with DDR2. I'm not sure why that is (instead of very much same per-clock performance), but it seems to support the doubt of DDR2 trumping DDR1 here.

For PowerBook G4 5,6 (1,67 GHz and DDR1 model) the Mplayer results are:

640x276 mov: 14,282 s
1280x544 mp4: 35,643 s

for a quick comparison - PowerBook 5,8 (1,67 GHz and DDR2 model) results are:

640x276 mov: 15,021 s
1280x544 mp4: 36,631 s

So it looks the results are pretty much the same (actually slightly slower for the DDR2 model, but I believe if the test were repeated a few times more we could get the same result).

> For PowerBook G4 5,6 (1,67 GHz and DDR1 model) the Mplayer results are: [...]
> PowerBook 5,8 (1,67 GHz and DDR2 model) results are: [...]
> So it looks the results are pretty much the same (actually slightly slower for
> the DDR2 model [...]).

Thanks. Pretty much as expected for G4 and in line with your previous DDR1 iBook vs. DDR2 PowerBook results scaled by me.

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Do you have any Benchmarks with Mplayer or Wayfarer running on G5 Quad vs G5 2.7?
And is there a difference on the Quad in Mplayer with faster GFX Card? Or are the results allways the same regardless which GPU (x800, 9800 or x19x0) you use?

>> PowerMac G5 PCIe 2,5 GHz is slightly faster (or slower) than
>> 2,7 GHz Dual Processor (except from [...] MPlayer benchmarks,
>> where it beats the AGP machine hands down)

> Do you have any Benchmarks with Mplayer [...] running on G5 Quad vs G5 2.7?

He does, in comment #10.

> is there a difference on the Quad in Mplayer with faster GFX Card? Or are the
> results allways the same regardless which GPU (x800, 9800 or x19x0) you use?

9800 won't work as X300 is the bottom PCIe-based Radeon card. That aside, I can't imagine a significant difference with regard to displaying video frames decoded by the CPU, but an actual test surely wouldn't hurt.

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Oh my fault. Didn't saw the Benchmark.
Impressive the Quad is much faster in mplayer.