[mpeg2] Re: question about the mpex and vbv buffer and vbv delay

[Luca Abeni <labeni@mbigroup.it>]

Hi Samuel,

[...]
>   Well, finally I've written that code. Using the decoding time to
> calculate the bitrate of the PES stream, the audio bitrate is perfectly
> constant, but the video's does not look constant at all. Plotting the
> result with xgraph you can see a saw with sharp teeth.
I did some other similar measurements, and my results are similar to
yours...

I was encoding CBR video at 4000kbps, MPEG1 layer 2 audio at 256kbps,
and I set the TS bitrate at 6000kbps.

After a lot of experiments, I tried to encode CBR video at 4000kbps,
audio at 256kbps, and to set the TS bitrate at 4500, and... It did the
trick! Now, the video bitrate is almost constant - but the ts analyzer
is complaining about buffer overruns and underruns... :(

>   I'm not sure if this is the correct way to see the bitrate of a PES
> stream, (maybe delving into the 13818-2 standard is required) but the results 
> agree with yours.
I don't know either... If someone knows the correct way, please let us
know... ;)

			Thanks,
				Luca
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