mpeg2 bitrate graph

[coordz]

I would like to see a graph of the frame by frame bitrate of an MPEG2 (program-)stream. I don't think gspot will do this. Software suggestions? MTIA

[PhillipWyllie]

Bitrate view, although I find it slow.

[coordz]

I agree, it is very slow and the free version will only load elementary streams (edit: because I was too dumb to change the file open option. opens program streams fine). Sort of does the job though. Thanks.

[jdobbs]

Frame-by-frame seems a little extreme. You'd find all the B frames to be low bitrate (because they are smaller) and all the I frames to be high bitrate. Would a GOP based bitrate display be enough?. Or am I missing something? Maybe you're talking about a cumulative average bitrate? I may be able to throw something together.

[coordz]

I'm encoding for DVD and want to ensure the MPEG2 streams I use are within spec, otherwise I must re-encode the streams. I'm not exactly sure how the spec phrases things (as I've never seen a copy ;)) but am interpreting the 9.8Mbps as frame-by-frame rate, although a per GOP or per second bitrate may be the correct one to use. I've also seen comments that going over 6Mbps for "long" (how long is long??) periods of time will stop the DVD working in some DVD players. Based on this, a graph of the bitrate would allow me to see if my VBR encodes have any "long" high bitrate periods and give me a feel for how hard I need to clamp the maximum bitrate.

[45tripp]

I may be able to throw something together.

if you're cooking, i'm eating

will stop the DVD working in some DVD players..

is there a reason for encoding/authoring with shitty hardware in mind? (even worse: rumors of such)

[coordz]

is there a reason for encoding/authoring with shitty hardware in mind? (even worse: rumors of such)

It's not so much shitty hardware but what the DVD spec says. If the spec says "all players must sustain 9.8Mbps" then everything is okay. If, on the other hand, the spec says "all players must sustain 6Mbps and cope with a burst rate of upto 9.8Mbps for xx seconds" then I'd like to know :) It's more of an academic question than anything because usually my encodes are a much lower bitrate to fit them on a DVD :cool:

[jdobbs]

I'm encoding for DVD and want to ensure the MPEG2 streams I use are within spec, otherwise I must re-encode the streams. I'm not exactly sure how the spec phrases things (as I've never seen a copy ;)) but am interpreting the 9.8Mbps as frame-by-frame rate, although a per GOP or per second bitrate may be the correct one to use. I've also seen comments that going over 6Mbps for "long" (how long is long??) periods of time will stop the DVD working in some DVD players. Based on this, a graph of the bitrate would allow me to see if my VBR encodes have any "long" high bitrate periods and give me a feel for how hard I need to clamp the maximum bitrate. The 9.8Mbs (combined with other values like audio, overhead, subtitles, etc.) is defined by the standard spin speed and disc read rate. The only thing you have to worry about is buffering -- and the authoring software should make sure you never have overflows or underflows. You can even get away with short bursts that exceed the max as long as the buffering can compensate for it.

If you use an MPEG encoder that has a setting for maximum bitrate and uses decent rate control, you shouldn't have to worry about it.

[coordz]

If you use an MPEG encoder that has a setting for maximum bitrate and uses decent rate control, you shouldn't have to worry about it.

I'm using ffmpeg with the '-target ntsc-dvd' flag. In Bitrate view the stream look perfectly acceptable bitrate-wise.