EC2 for video-encoding

Question

I have a potential job which will require me to do some video encoding with FFMPEG and x264. I'll have a series of files which I'll need to encode once, then I'll be able to bring down the instances. Since I'm not really sure of the resource utilization of x264 and FFMPEG, what kind of instances should I get? I'm thinking either a

High-CPU Extra Large Instance

7 GB of memory
20 EC2 Compute Units (8 virtual cores with 2.5 EC2 Compute Units each)
1690 GB of instance storage
64-bit platform
I/O Performance: High
API name: c1.xlarge

or, alternatively a

Cluster GPU Quadruple Extra Large Instance

22 GB of memory
33.5 EC2 Compute Units (2 x Intel Xeon X5570, quad-core “Nehalem” architecture)
2 x NVIDIA Tesla “Fermi” M2050 GPUs
1690 GB of instance storage
64-bit platform
I/O Performance: Very High (10 Gigabit Ethernet)
API name: cg1.4xlarge

What should I use? Does x264/FFMPEG perform better with faster/more CPUs or does it really pound the GPU more? In any case, it seems that the Cluster GPU seems to be the higher performance instance. What should I prefer?

Answer 1

Ffmpeg recently added support for VAAPI and VDPAU, but this allows it to use the GPU only for decoding of H.264 video. For encoding, it uses the CPU.