mpeg gain a la mp3?

[drcl]

This might be a totally dumb question.

Is there a way of manipulating an mpeg video stream to change the luminance and chrominance gain like how you can do with mp3 volume?

seems like everything is based on co-efficients so wouldnt it be possible to adjust the contrast without re-encoding?

[Mug Funky]

if your encode was constant quant (including b-frames, and no adaptive quant at all like lumi-masking et al), then you'd stand a chance.

although, i doubt it'd decode correctly - there'd be overflows and stuff, probably lots of black blocks in white areas and white blocks in black areas.

[edit]

maybe a compressed-domain-transcoder could handle it? it decompresses all that stuff anyway. you'd lose quality though - probably as much as a complete re-encode, possibly less (though i wouldn't bet on it).

[drcl]

its just something i thought of....

i guess the 2 arent that similar (mp3 and mpeg video) even though they both use DCTs