change vbv parameters in mpeg2 stream

[Sagittaire]

How apply vbv buffer and max bitrate in mpeg2 elementary stream?

If there are not tool I can make that with hexadecimal heditor but I don't know how find the good flag in the stream (replace ? by ?)

[Guest]

Why do you need to do that?

[Sagittaire]

When you actived these parameters in Libavcodec you change totaly the Rate Control and not only for potentialy vbv saturation part. I want try to produce compliant vbv stream only with qcomp tweak (curve compression quantizer) and after set the vbv parameters in the bitstream. It's just to obtain the best possible quality with MPEG2 for test application ...

[Guest]

You can't just arbitrarily change the VBV buffer size. The encoding process produces a stream that requires a certain minimum size VBV buffer. If you make it too small, the buffer will overflow and decoding will be hosed. If you make it too large you just have extra unused memory. So I don't understand what you are trying to accomplish by changing VBV buffer size after the stream is already encoded.

The bitrate value specifies the maximum bitrate. Most decoders don't even use that field. Again, I don't understand your intent here.

You could hack up DGPulldown as I did for modifying the profile/level fields. Using a hex editor is a non-starter because the fields are repeated periodically in the stream. It would take forever to modify a stream that way.