[x264-devel] default level

[Loïc Le Loarer]

Hi everybody,

I'm seeing many many H.264 streams encoded with x264 in 5.1 level,
because it is the default level. The problem is that some decoders
doesn't play correctly those files because they don't support this
level.

So I'm wondering if using level 5.1 as the default level is a good idea.
There is exactly zero decoder on the market which are 5.1 compliant,
most HD decoders in set top boxes, DMA... are 4.0 or 4.1 compliant. So
using 5.1 by default means that most people encoding streams produce
unplayable streams.

I know that most of the time, it is possible for a 4.0 decoder to decode
a 5.1 stream encoded by x264 because the stream is 1080p30 at most, so
the only difference between 4.0 and 5.1 levels in this case is the
memory requirement for the decoder (MaxDPB size). But some hardware
decoders doesn't have enough memory...

A simple solution is to just set the default level to 4.0. or 4.1, a
better solution would be to adjust the level (if not requested by the
user) to the lowest level according to the requested frame size, frame
rate and bitrate. I know it is not perfect but it will work in most
cases.

How would you apreciate such a patch ?

Thank you in advance,
-- 
Loïc

"heaven is not a place, it's a feeling"
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