[FFmpeg-trac] #2136(avcodec:new): libvpx -crf option is broken

[FFmpeg]

#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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