[FFmpeg-user] web videos with flv

Reindl Harald h.reindl at thelounge.net
Fri Feb 17 20:43:21 CET 2012

Am 17.02.2012 20:19, schrieb Lou:
>> but however, i played around many days and nights with all sorts of
>> input files convert them for Flash-Player/HTML5-<video> and this
>> was the most perfect combination built in our php-ffmpeg-wrapper
>> ffmpeg -i 'infile.avi' -y -vb '448k' -ab '96k' -bt '32k' -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'
>> -timestamp 'now' 'outfile.mp4'
> Declaring each x264 option is not recommended. That's what the presets
> are for (example: "-preset medium", see "x264 --help" for a full list o'
> presets). 

if they would not change all the time by name of
present and how the param is called, i can not
and will not maintain my wrapper-lib for different
ffmpeg-versions - currently it works with 0.6-0.10
with all libx264 versions of the last 4 years

> Using presets is easier and allows you to keep up with any
> changes if you update FFmpeg/x264

see abvoe, only in theory

> and ffmpeg probably ignores some of
> these old options (but not if they are implemented via -preset). The
> presets save you time because they were designed by the x264 developers,
> who know what they are doing, so you no longer have to monkey with
> dozens of settings and end up with options that make no sense. The
> closest preset equivalent for your example would be "slow" or "medium"
> followed by "-profile:v baseline".

i have two built-in presets for 'baseline' and 'main'
also supporting two-pass-encoding with optimized
x264 and no-audio params for the first pass

> If you feel like the presets are not adequate for your purposes they
> are still useful as you can overwrite preset options with x264opts or
> several libx264 private options (listed in "ffmpeg -h"), but I don't
> recommend changing preset settings unless you know what you are doing.

but i know what i am doing

> Also, I believe libx264 ignores "-bt"


> Why not "-threads "0" (auto
> choose appropriate thread value)? 

because the command-line is from a logfile

most of params like bitrate are controlled by app-settings
and enforced by my wrapper-library

threads is usually set by environemnt-variable per machine
this stuff is mostly running on webservers and if the virtual
machine has tzwo vCPU's ffmpeg must not use more than two
of them, if it has 8 it is configured to use up to 4 to
consume not more than 1/2 CPU power, the rest is for httpd/mysql

> "mv4" is used with the "mpeg4"
> encoder, not libx264, IIRC.

in reality i am using .mp4

but ffmpeg gives you a warning with "-f ipod" that apple-devices
may refuse videos not having .m4v (i am not willing to change this
now in all applications i wrote the last years but decided to
use on the mailing-list the recommended extension)

however - in suammy this all is MPEG4

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