[x264-devel] Generating H264 for iPad?

[Jason Garrett-Glaser]

On Thu, Feb 23, 2012 at 7:24 AM, Reindl Harald <h.reindl at thelounge.net> wrote:
>
>
> Am 23.02.2012 16:13, schrieb Jason Garrett-Glaser:
>>
>> This commandline is a massive pile of junk and anyone who uses it is
>> beyond clueless.
>>
>> Use the -preset, -profile, etc options, not a huge pile of cargo-cult options.
>
> but it works
>
> the damned -preset / -profile parameters including their
> x264-values are changing permanently - this way you can
> NEVER make a useful wrapper without maintain hughe
> code-switches and ways control them by a specific
> ffmpeg-version

I have no idea what you're even saying here.  The -preset/-profile
names have never changed since their introduction many years ago.
ffmpeg has had per-codec option support for ages now too, so there
really isn't any excuse to continue this mess.

Please stop spreading bad advice on the mailing list.

For specifics:

>>> ffmpeg -i 'inputfile.mp4' -y -vb '448k' -ab '96k' -ar '44100' -ac '2' -r '25' -async '1' -maxrate '544k' -f 'ipod'
>>> -vcodec 'libx264' -acodec 'libfaac' -flags '+loop+mv4' -cmp '256' -partitions
>>> '+parti4x4+parti8x8+partp4x4+partp8x8+partb8x8' -me_method 'hex' -me_range '16' -subq '7' -trellis '1' -refs '5' -g
>>> '250' -keyint_min '25' -sc_threshold '40' -i_qfactor '0.71' -qcomp '0.6' -qmin '0' -qmax '69' -qdiff '4' -bufsize
>>> '2M' -directpred '3' -rc_lookahead '50' -threads '2' -coder '0' -bf '0' -flags2 '-wpred-dct8x8' -wpredp '0'
>>> 'outputfile.mp4'

1.  You're using ABR mode, which is strongly discouraged.
2.  async 1 is set for absolutely no reason.  Does that option even
exist anymore?
3.  +mv4 doesn't even do anything.
4.  At least half of those options do nothing, because they are the defaults.
5.  You are crippling x264's speed by reducing the number of threads.
6.  Your bufsize is chosen without any apparent reason.  It doesn't
match any typical number of seconds either.
7.  You have some options enabled that are pointless except at very
insane speed settings (e.g. p4x4).

Seriously, why?

Jason