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

[Christian Ebert]

* Christian Ebert on Thursday, December 02, 2010 at 22:47:41 +0100
> ---
> ffpresets/libx264-ipod320.ffpreset |    1 +
> 1 files changed, 1 insertions(+), 0 deletions(-)
> 
> diff --git a/ffpresets/libx264-ipod320.ffpreset b/ffpresets/libx264-ipod320.ffpreset
> index 943b521..9191ff4 100644
> --- a/ffpresets/libx264-ipod320.ffpreset
> +++ b/ffpresets/libx264-ipod320.ffpreset
> @@ -1,5 +1,6 @@
> coder=0
> bf=0
> +refs=1
> flags2=-wpred-dct8x8
> level=13
> maxrate=768000

I actually did some testing wrt to refs on iPod, although I have
only 1 device: iPod Touch 3.1.3 16GB. The value can perhaps
increased to 2, at least for ipod640. ref=3 definitely does not
work reliably, as my broken sample proves:

http://www.blacktrash.org/downloads/tmp/ffmpeg/test-refs3.m4v
Screenshot:
http://www.blacktrash.org/downloads/tmp/ffmpeg/test-refs3.png

It would be great if we could do more testing of

http://www.blacktrash.org/downloads/tmp/ffmpeg/test-refs2.m4v

especially on ipod classic. Apparently it depends a lot of the
material. With less movement or panning in the source might get
away with higher values:

http://blog.dest-unreach.be/2009/09/08/h264-limits-for-iphone/

But refs=1 is certainly safe, refs=2 might be.

c
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