mp4 muxer supports VBR ?

mp4 muxer supports VBR ?

Hi,
I would like to use the mp4 muxer from the IPP samples, but on the readme.htm it says:
Known Limitations

  • Streams encoded with variable bit rate (VBR) are not supported in current version.

I was able to mux a h.264 variable bit rate video stream to the MP4 muxer and view it via vlc/wmp. Is this limitation in IPP V6 still valid ? Or can someone explain what this limitation means in this case ?

I used the H.264 encoder from IPP and set the following parameters:

Params.info.clip_info.height=imgHeight; Params.info.clip_info.width=imgWidth;
//Params.info.bitrate = 1000000;
Params.rate_controls.method = UMC::H264_Rate_Control_Method::H264_RCM_QUANT;
Params.rate_controls.quantI = 21;
Params.rate_controls.quantP = 21;
Params.rate_controls.quantB = 21;
Params.numThreads = 1;
if((status = H264Encoder.Init(&Params))!=UMC::UMC_OK)

Thanks for any help !

Best regards

mb701

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Ritratto di Pavel V.Vlasov (Intel)

Good day.

This readme file is probably out of date. MP4Muxer can mux VBR streams.

> Params.rate_controls.method = UMC::H264_Rate_Control_Method::H264_RCM_QUANT;

This is not VBR, this is constant quantization without rate control. For VBR encoding you need to use H264_RCM_VBR.

Have a nice day.

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