[FFmpeg-devel] CBR Bitrate control in MPEG-2 video encoder
Wed May 26 21:54:01 CEST 2010
Am 26.05.2010 21:30, schrieb Michael Niedermayer:
> 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.
Yes ok. :-)
But how calculate the ffmpeg cmd tool the showed bitrate during
encoding? I guess without the knowledge of the mpeg-2 vbv model?
>>> 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
Ok, and how is ensured that the ffmpeg MPEG-2 video encoder fullfills
the specs for vbv? Was there a test with a
true mpeg2 stream analyzer and the result was fine for a set test streams?
More information about the ffmpeg-devel