[Ffmpeg-devel] [PATCH] Update docs according to new "ab" parameter unit

Benoit Fouet benoit.fouet
Tue Mar 6 08:43:48 CET 2007


Hi Takis,

Panagiotis Issaris wrote:
> Hi,
>
> The attached patch updates the documentation to be consistent with the
> new unit for the "ab" parameter.
>
i was about to send it too :)

> Index: doc/faq.texi
> ===================================================================
> --- doc/faq.texi	(revision 8268)
> +++ doc/faq.texi	(working copy)
> @@ -171,7 +171,7 @@
>  @item non-working stuff
>  B-frames
>  @item example command line
> -ffmpeg -i input -acodec aac -ab 128 -vcodec mpeg4 -b 1200kb -mbd 2 -flags +4mv+trell -aic 2 -cmp 2 -subcmp 2 -s 320x180 -title X output.mp4
> +ffmpeg -i input -acodec aac -ab 128kb -vcodec mpeg4 -b 1200kb -mbd 2 -flags +4mv+trell -aic 2 -cmp 2 -subcmp 2 -s 320x180 -title X output.mp4
>   
well, if you update this, you have also to change "-b" to "-vb"
in fact, the behaviour now is that one:
- "ab" option sets audio bitrate
- "vb" option sets video bitrate
- "b" option sets both
so, if we have on the same line a "ab" option followed by a "b"
option... the latter will overwrite the former...

>  @end table
>  
>  @section How do I encode videos which play on the PSP?
> @@ -184,7 +184,7 @@
>  @item non-working stuff
>  B-frames
>  @item example command line
> -ffmpeg -i input -acodec aac -ab 128 -vcodec mpeg4 -b 1200kb -ar 24000 -mbd 2 -flags +4mv+trell -aic 2 -cmp 2 -subcmp 2 -s 368x192 -r 30000/1001 -title X -f psp output.mp4
> +ffmpeg -i input -acodec aac -ab 128kb -vcodec mpeg4 -b 1200kb -ar 24000 -mbd 2 -flags +4mv+trell -aic 2 -cmp 2 -subcmp 2 -s 368x192 -r 30000/1001 -title X -f psp output.mp4
>   
ditto

>  @item needed stuff for H.264
>  -acodec aac -vcodec h264 width*height<=76800 width%16=0? height%16=0? -ar 48000 -coder 1 -r 30000/1001 or 15000/1001 -f psp
>  @item working stuff for H.264
> @@ -192,7 +192,7 @@
>  @item non-working stuff for H.264
>  CAVLC
>  @item example command line
> -ffmpeg -i input -acodec aac -ab 128 -vcodec h264 -b 1200kb -ar 48000 -mbd 2 -coder 1 -cmp 2 -subcmp 2 -s 368x192 -r 30000/1001 -title X -f psp -flags loop -trellis 2 -partitions parti4x4+parti8x8+partp4x4+partp8x8+partb8x8 output.mp4
> +ffmpeg -i input -acodec aac -ab 128kb -vcodec h264 -b 1200kb -ar 48000 -mbd 2 -coder 1 -cmp 2 -subcmp 2 -s 368x192 -r 30000/1001 -title X -f psp -flags loop -trellis 2 -partitions parti4x4+parti8x8+partp4x4+partp8x8+partb8x8 output.mp4
>   
ditto

>  @end table
>  
>  @section Which are good parameters for encoding high quality MPEG-4?
> Index: doc/ffmpeg-doc.texi
> ===================================================================
> --- doc/ffmpeg-doc.texi	(revision 8268)
> +++ doc/ffmpeg-doc.texi	(working copy)
> @@ -117,7 +117,7 @@
>  mapping from input stream to output streams:
>  
>  @example
> -ffmpeg -i /tmp/a.wav -ab 64 /tmp/a.mp2 -ab 128 /tmp/b.mp2 -map 0:0 -map 0:0
> +ffmpeg -i /tmp/a.wav -ab 64k /tmp/a.mp2 -ab 128k /tmp/b.mp2 -map 0:0 -map 0:0
>  @end example
>  
>  Converts a.wav to a.mp2 at 64 kbits and to b.mp2 at 128 kbits. '-map
> @@ -127,7 +127,7 @@
>  * You can transcode decrypted VOBs
>  
>  @example
> -ffmpeg -i snatch_1.vob -f avi -vcodec mpeg4 -b 800k -g 300 -bf 2 -acodec mp3 -ab 128 snatch.avi
> +ffmpeg -i snatch_1.vob -f avi -vcodec mpeg4 -b 800k -g 300 -bf 2 -acodec mp3 -ab 128k snatch.avi
>  @end example
>  
>  This is a typical DVD ripping example; the input is a VOB file, the
> @@ -560,7 +560,7 @@
>  @item -ar freq
>  Set the audio sampling frequency (default = 44100 Hz).
>  @item -ab bitrate
> -Set the audio bitrate in kbit/s (default = 64).
> +Set the audio bitrate in bit/s (default = 200k).
>  @item -ac channels
>  Set the number of audio channels (default = 1).
>  @item -an
> @@ -578,7 +578,7 @@
>  
>  Example:
>  @example
> -ffmpeg -i file.mpg -vcodec copy -acodec ac3 -ab 384 test.mpg -acodec mp2 -ab 192 -newaudio
> +ffmpeg -i file.mpg -vcodec copy -acodec ac3 -ab 384k test.mpg -acodec mp2 -ab 192k -newaudio
>  @end example
>  @item -alang code
>  Set the ISO 639 language code (3 letters) of the current audio stream.
>   
>   
Ben





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