Target usage

[Krist]

Hello,

What exactly does the target usage setting do? I'm noticing that if I use "BEST_QUALITY" with a bitrate of 4mbit, sometimes the encoder is not fast enough to keep up with a live stream (24 fps).

However, when I am using "BALANCED" with a bitrate of 50mbit, there is no such speed issue.

I'd like to know what exactly the targetusage setting is doing, since it is also not documented anywhere.

I'm using a

Intel(R) Core(TM) i7-4700EQ CPU @ 2.40GHz

if that matters.

[Jeffrey_M_Intel1 · Accepted solution]

TargetUsage (TU) is similar to the "preset" concept in FFmpeg.  It provides a quick way to change quality/speed tradeoffs in codec settings.

Assuming you're looking at H264, a TU range of 1-7 is available. 

• 1=Best quality (but lowest performance)
• 2=quality boost vs. TU4 at cost of speed
• 4=settings calibrated for preserving quality and speed
• 6=speed boost vs. TU4 at slightly lower quality
• 7=best speed (but with larger quality drop) 

(With TU 3 and 5 as points between those described above.)

Here are some starting points which have more info on TargetUsage behavior:

• https://software.intel.com/sites/default/files/New-Flexible-High-Efficient-Intel-Iris-Iris-Pro-Quick-Sync-Video.pdf
• http://www.intel.com/content/dam/www/public/us/en/documents/white-papers/cloud-computing-quicksync-video-ffmpeg-white-paper.pdf

The next level of detail is harder to get because it can change between hardware and driver versions.  However, the relationships between the TUs should remain similar to the references above.  Is this sufficient information?

Regards, Jeff

[Krist]

Thank you Jeff, that's enough information. I will have to fine-tune the setting to find the perfect fit for my application. I understand now also that the behavior may be different for each type of hardware.

Best regards,

Chris