[x264-devel] [PATCH] Relaxed parameter checking at encoder/encoder.c

[Marco Aurélio Graciotto Silva]

Dear x264 developers,

Lately, I'm trying to compress some movies using MPEG-4 AVC
Predictive Profile (aka lossless compression). I wasn't using
x264 directly, but FFmpeg. Then I strumbled across an issue
regarding some parameters that FFmpeg defined by itself and
which, when using x264 in lossless mode, results in an error:
'broken ffmpeg default settings detected'. Further information
and instructions to reproduce this are described at
http://permalink.gmane.org/gmane.comp.video.ffmpeg.user/29323

I traced the issue to encoder/encoder.c, more precisely at
line 471, in a block of code that, as its comment says, "Detect
default ffmpeg settings and terminate with an error."

>From the FFmpeg side, I can workaround this by setting
some parameters (such as qmin, qmax, etc), even though
such parameters will be overriden by x264 (because of the
lossless mode).

However, a better solution would be to, in the code that x264 tries
to detect FFmpeg defaults, ignore some parameters that will be
overwritten anyway in lossless mode. I created a patch
x264-lossless-ffmpeg_parameter_check.patch and it worked
just fine here. Is it okay?


Regards,

Marco Aurélio
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