[FFmpeg-devel] CBR Bitrate control in MPEG-2 video encoder

Michael Niedermayer michaelni
Wed May 26 21:30:30 CEST 2010

On Wed, May 26, 2010 at 09:22:18PM +0200, Sven Brandau wrote:
> Am 25.05.2010 23:30, schrieb Michael Niedermayer:
>> cbr (constant bitrate) does not mean constant framesize
>> the bitrate that enters the vbv should be constant
> And how are you measure the bitrate? In a very simple way you will take the 
> whole time of the video stream and calculate the bitrate from file size. 
> The only question is (beside the vbv constrains) how small is the time unit 
> in which the bitrate will be calculated. 1s? 30s? ...?

you must read and understand the mpeg specs and how vbv works, this discussion
is pointless otherwise.

>> and only a true mpeg2 stream analyzer can tell you the bitrate prior to
>> the vbv. Your mail does not sound like you used such a tool
> You are right, I don't have such a tool. Have you ever tried such a tool on 
> the ffmpeg MPEG-2 video encoder?

some people did


Michael     GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB

There will always be a question for which you do not know the correct awnser.
-------------- next part --------------
A non-text attachment was scrubbed...
Name: not available
Type: application/pgp-signature
Size: 189 bytes
Desc: Digital signature
URL: <http://lists.mplayerhq.hu/pipermail/ffmpeg-devel/attachments/20100526/befc2e99/attachment.pgp>

More information about the ffmpeg-devel mailing list