[FFmpeg-user] Is there a better way to do this

Reindl Harald h.reindl at thelounge.net
Sat Apr 19 13:01:50 CEST 2014



Am 19.04.2014 12:52, schrieb Cecil Westerhof:
> Op Saturday 19 Apr 2014 12:40 CEST schreef Reindl Harald:
> 
>> Am 19.04.2014 12:31, schrieb Cecil Westerhof:
>>> I am using:
>>> ffmpeg -async 1
>>> -f alsa
>>> -ac 1
>>> -i hw:1,0,0
>>> -f x11grab -s 1920x1080
>>> -r 25
>>> -i :0.0
>>> -acodec libmp3lame
>>> -ar 22050
>>> -ab 64k
>>> -qscale:video 4
>>> 2014-04-19_12:24.avi
>>>
>>> Works reasonably well. But in the man page I do not see the
>>> parameter '-ab' described. Should I use something else for this?
>>
>> ab = AudioBitrate
>> http://en.wikipedia.org/wiki/MP3
> 
> Why is it then not in the documentation?

other question: why do you set params don't know what they are?

because it is disapproved, exists because of compatibility
as well as "vb" for video-bitrate while recent versions
prefer -b:v and -b:a, ffmpeg --help is a good start in doubt

a simle google search answers that in the search results
https://www.google.com/search?q=ffmpeg+%22-ab%22

Video options:
-vframes number     set the number of video frames to record
-r rate             set frame rate (Hz value, fraction or abbreviation)
-s size             set frame size (WxH or abbreviation)
-aspect aspect      set aspect ratio (4:3, 16:9 or 1.3333, 1.7777)
-bits_per_raw_sample number  set the number of bits per raw sample
-vn                 disable video
-vcodec codec       force video codec ('copy' to copy stream)
-timecode hh:mm:ss[:;.]ff  set initial TimeCode value.
-pass n             select the pass number (1 to 3)
-vf filter_graph    set video filters
-b bitrate          video bitrate (please use -b:v)
-dn                 disable data

Audio options:
-aframes number     set the number of audio frames to record
-aq quality         set audio quality (codec-specific)
-ar rate            set audio sampling rate (in Hz)
-ac channels        set number of audio channels
-an                 disable audio
-acodec codec       force audio codec ('copy' to copy stream)
-vol volume         change audio volume (256=normal)
-af filter_graph    set audio filters

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