[FFmpeg-devel] [PATCH] ipod320: restrict to refs=1 as in ipod640 (issue2399)

Christian Ebert blacktrash
Fri Dec 3 16:53:35 CET 2010

* Niobos on Friday, December 03, 2010 at 16:39:34 +0100
> On 2010-12-02 23:03, Christian Ebert wrote:
>> Apparently it depends a lot of the
>> material. With less movement or panning in the source might get
>> away with higher values:
> If it depends on the material, it's not a problem with the number of
> references, but (usually) with the bitrate being too low.

But I encoded my samples with exactly the same bitrate (and all
other settings as well). The _only_ difference was the number of
references. Anything higher than 2 refs was broken.

But I will try with a higher bitrate.

> The number of refs simply specifies how many frames back the motion
> vectors can point; and hence how many decoded frames the decoder needs
> to store. Since these frames are decoded, the complexity (movement) does
> not matter.

In theory there is no difference between theory and practice ;-)
Sorry, I'm having a hard time understanding.

And where does the refs=1 in libx264-ipod640.ffpreset come from?

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