#2136: libvpx -crf option is broken
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Reporter: evilsoup | Owner:
Type: defect | Status: new
Priority: normal | Component: avcodec
Version: git-master | Resolution:
Keywords: libvpx | Blocked By:
Blocking: | Reproduced by developer: 0
Analyzed by developer: 0 |
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Comment (by slhck):
The error is that the minimum quantizer value is 4 by default. If you set
any CRF value below that, it simply doesn't make sense.
Users should be able to override this by setting `-qmin` to 0, however
with the current code this is not possible, since `qmin` can only be set
to anything larger than 0.
{{{libvpxenc.c}}}, line 288 should therefore be:
{{{
if (avctx->qmin >= 0)
}}}
instead of
{{{
if (avctx->qmin > 0)
}}}
Because of this bug, the only workaround is to set a `-qmin` of 1 and,
consequently, a CRF of 1 will work.
Also, the check for `qmax` should include `if (avctx->qmax > avctx->qmin)`
as well, since it can never be lower than `qmin`.
--
Ticket URL: <https://ffmpeg.org/trac/ffmpeg/ticket/2136#comment:2>
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