Bitrate peaks to just under 10mb/s, is this ok for cheap dvd players?

[rosiestarr]

I am trying to make a commercial DVD that will be replicated, which I have encoded using HCencoder. My average bitrate is 7.2mb/s and my maximum is 9mb/s. Despite this, Bitrate Viewer is saying that my m2v file is peaking at 9797kbps. I am just wondering if this is totally safe for cheap/old dvd players, or if I could run into any issues? (My audio is 192kbs ac3.)

If so, any ideas why it is peaking so high when my max is set to 9mb/s? Thank you.

[poisondeathray]

Maybe, it depends on the cheap player

But the technical answer is you can't use bitrate viewer to evaluate "peaks" for devices like DVD players. The reason is they have a buffer, and it's really a matter of input /output equation that depends on the input rate (reading from disk), output requested data (decoded image), and current buffer level. So if it's a buffered peak , that doesn't drain the current buffer level it might be ok. You would need a buffer analyzer to check

[jagabo]

Ie, bitrate viewer looks at fixed sized blocks at fixed intervals. For example in "1 second" mode it looks at 1 second long blocks at 1 second intervals. For a 25 fps video it calculates the average bitrate of frames 0 to 24, then the average of frames 25 to 49, then frames 50 to 74, etc The peak bitrate it reports is highest value it found.

That's not how a DVD player sees the video. The DVD player sees a sliding window. Say the window is 8 frames. At the first frame the bitrate it sees is the average of frames 0 through 7. At the second frame the bitrate is the average of frames 1 through 8, at the third frame the bitrate is the average of frames 2 through 9, etc.

[rosiestarr]

Ie, bitrate viewer looks at fixed sized blocks at fixed intervals. For example in "1 second" mode it looks at 1 second long blocks at 1 second intervals. For a 25 fps video it calculates the average bitrate of frames 0 to 24, then the average of frames 25 to 49, then frames 50 to 74, etc The peak bitrate it reports is highest value it found.

That's not how a DVD player sees the video. The DVD player sees a sliding window. Say the window is 8 frames. At the first frame the bitrate it sees is the average of frames 0 through 7. At the second frame the bitrate is the average of frames 1 through 8, at the third frame the bitrate is the average of frames 2 through 9, etc.

SO this would suggest that I shouldn't have a problem with my DVD peaking like this?

[jagabo]

Ie, bitrate viewer looks at fixed sized blocks at fixed intervals. For example in "1 second" mode it looks at 1 second long blocks at 1 second intervals. For a 25 fps video it calculates the average bitrate of frames 0 to 24, then the average of frames 25 to 49, then frames 50 to 74, etc The peak bitrate it reports is highest value it found.

That's not how a DVD player sees the video. The DVD player sees a sliding window. Say the window is 8 frames. At the first frame the bitrate it sees is the average of frames 0 through 7. At the second frame the bitrate is the average of frames 1 through 8, at the third frame the bitrate is the average of frames 2 through 9, etc.

SO this would suggest that I shouldn't have a problem with my DVD peaking like this?

No, it doesn't suggest that.

To reduce the amount of work for this example let's use a 4 frame window for both. Say a video has per frame bitrates of:

1000, 1000, 15000, 15000, 15000, 15000, 1000, 1000

Bitrate viewer gives you the average of the first 4 frames, then the average of the next four frames:

8000, 8000

The peak bitrate viewer reports is 8000. That doesn't seem to be a problem for DVD.

But the DVD players sees:

8000, 11500, 15000, 11500, 8000

So the peak the DVD player sees is 15000, not the 8000 bitrate viewer reported.

[Cornucopia]

Jagabo is correct. It only suggests that you are using the wrong tools to determine your DVD bitrate compliancy.

IIWY, I'd bypass this whole problem and maintain DVD compliancy by re-encoding with 2pass VBR using a max of 9.8mbps (minus audio&subs bitrates) and an avg that will allow you to fit it on the disc given your running time. Solved!

Scott

[rosiestarr]

Jagabo is correct. It only suggests that you are using the wrong tools to determine your DVD bitrate compliancy.

IIWY, I'd bypass this whole problem and maintain DVD compliancy by re-encoding with 2pass VBR using a max of 9.8mbps (minus audio&subs bitrates) and an avg that will allow you to fit it on the disc given your running time. Solved!

Scott

But this is exactly what I've done. 2pass VBR, Average 7.2mbs and Max 9mbs?

[Skiller]

As a test, author the video + audio streams with Muxman.
If Muxman does not abort with an error message ("Multiplex operation failed: Probably caused by excessive bitrate"), the buffers are fine and bitrate peaks are within DVD spec. In my opinion this is the most reliable way to find out if the bitrate is within spec or not because, as already explained, bitrate viewers see the data differently.

[rosiestarr]

As a test, author the video + audio streams with Muxman.
If Muxman does not abort with an error message ("Multiplex operation failed: Probably caused by excessive bitrate"), the buffers are fine and bitrate peaks are within DVD spec. In my opinion this is the most reliable way to find out if the bitrate is within spec or not because, as already explained, bitrate viewers see the data differently.

Amazing! I carried out this test and muxman returned no error. Thanks a lot for this

[PuzZLeR]

SO this would suggest that I shouldn't have a problem with my DVD peaking like this?

No, it doesn't suggest that.

To reduce the amount of work for this example let's use a 4 frame window for both. Say a video has per frame bitrates of:

1000, 1000, 15000, 15000, 15000, 15000, 1000, 1000

Bitrate viewer gives you the average of the first 4 frames, then the average of the next four frames:

8000, 8000

The peak bitrate viewer reports is 8000. That doesn't seem to be a problem for DVD.

But the DVD players sees:

8000, 11500, 15000, 11500, 8000

So the peak the DVD player sees is 15000, not the 8000 bitrate viewer reported.

Good explanation. Such spikes, which can indeed be problematic in DvD playback, can hide in the numbers, making Bitrate Viewer essentially useless.

Leave such sketchy number reporting to the accountants.