ICQ Rate Control on hevc_qsv?

Is it possible to invoke ICQ rate control for export in the hevc_qsv codec on Windows? If so, how is it done?

Thanks for this great app!

You need to get Shotcut/Melt to pass-thru the parameter “-global_quality 25” and possibly the parameter “-look_ahead 1” to FFmpeg.

I’m not 100% sure but you may be able to do this under the “Other” tab in the Export window by adding:


You could try it and see.

Yeah, I thought of that myself, but it doesn’t seem to work. Here are the relevant lines from the log:

[hevc_qsv @ 000001b13a86d040] Initialized an internal MFX session using hardware accelerated implementation

[hevc_qsv @ 000001b13a86d040] Using the constant quantization parameter (CQP) ratecontrol method

[hevc_qsv @ 000001b13a86d040] profile: simple; level: 30

[hevc_qsv @ 000001b13a86d040] GopPicSize: 150; GopRefDist: 4; GopOptFlag: closed ; IdrInterval: 1

[hevc_qsv @ 000001b13a86d040] TargetUsage: 4; RateControlMethod: CQP

[hevc_qsv @ 000001b13a86d040] QPI: 12; QPP: 16; QPB: 21

[hevc_qsv @ 000001b13a86d040] NumSlice: 1; NumRefFrame: 3

[hevc_qsv @ 000001b13a86d040] RateDistortionOpt: unknown

[hevc_qsv @ 000001b13a86d040] NumTileColumns: 1; NumTileRows: 1

[hevc_qsv @ 000001b13a86d040] RecoveryPointSEI: unknown IntRefType: 0; IntRefCycleSize: 0; IntRefQPDelta: 0

[hevc_qsv @ 000001b13a86d040] MaxFrameSize: 0; MaxSliceSize: 0;

[hevc_qsv @ 000001b13a86d040] BitrateLimit: unknown; MBBRC: OFF; ExtBRC: OFF

ICQ is not used due to compatibility issues. However, you can make it work by saving the export job’s XML and editing the <consumer> tag to remove qscale and add global_quality. Then, run it with the melt executable that comes with Shotcut in a terminal window. If you are running a locale that uses a comma for the decimal point, also set the environment variable LC_ALL=C.

Thanks! Makes perfect sense.

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