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H264 Encode - quantization

Mordehay Hilu
Prodigy 120 points

Hi,

Can someone reccomand on the optimal value of the Qunatization? We see that when setting high level, there are cases that the encode has very high bit rate peaks. On the other hand, too low level causes to degradation in picture quality.

 

Thanks in advance,

 

  • TI__Genius 17215 points

    Hi,

    The answer lies in what is acceptable to you. What you said will of course happen when you use fixed QP. Does you application need fixed QP ? Can you use rate control and tell the bitrate to codec and let codec decide what is the best QP.

    whcih platform is this ?

    regards

    Yashwant

  • in reply to Yashwant Dutt
    Prodigy 120 points

    Hi,

    My system is based on the DM6467 which is used as an H264 encoder, which sends a stream over the local network. We notice that even if we use CBR, there are major jumps in the bit rate which cause us problems. We also noticed that lowering the Quantization leads to lower bit rate peaks. So my basic problem is how to eliminate high bit rate peaks (I can find a content that causes to peaks of above 50Mbps). I tried to play with some cotents and quantization values and it seems that level of about 35 give reasonable results (yet there are high peaks in the bit rate).

  • in reply to Mordehay Hilu
    TI__Genius 17215 points

    The peak in the bitrate for CBR may be coming due to periodic intra frames, Can you please check if that is the case ? Can you send a sample stream so that we can analyze.

    regards

    Yashwant