MP4 video files on DVD, keeping bit rate above source

[Much2Learn]

Hi all,

I'll start by saying that I've read a lot at this point and I'm completely overwhelmed by the amount of information there is. I somewhat have the fundamentals down, but now I'm at a point where I need to ask some questions.

I have 13 video files, 3.39 GB in size totaling 4:35:36 in length. They are 720x480 with an average bit rate of 1800 kbps (audio averages 110 kbps). I'm using DVD Flick to author. With all the files on one disc, DVD Flick marks it as 98% full with a bit rate of 2000 kbps.

My question is this: am I doing myself a disservice by putting all the files on one DVD5, or am I not really losing anything since the bit rate is staying above their bit rate? Am I cutting it too close with the audio/menus factored in?

[videobruger]

You should use 2 discs.

It's not just a question of bitrate but also the codec used. For DVD that's a subset of MPEG-2 which is not very efficient, ie demands high bit rate for good quality. Your source MP4's migth have h.264 which is a much more efficient codec.

[Much2Learn]

Yes, according to VLC, this is the codec information:

Stream 0
Type: Video
Codec: H264 - MPEG-4 AVC (part 10) (avc1)
.
.
.
.
Decoded format: Planar 4:2:0 YUV

Stream 1
Type: Audio
Codec: MPEG-AAC (Audio) (mp4a)
.
.
.

So splitting it to two discs, I can average about 4000 kbps. Will I lose quality at this bit rate as compared to 7000 kbps, for example?

[Southstorm]

4000 kbps average should give you decent quality.

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[videobruger]

Try make a test with 4 Mb/s and 7 Mb/s and see what you think. I'm not a user of DVD Flick but it can set the target bitrate in Project Settings.

[Southstorm]

The DVD specs has limitations as to how much bitrate you can use. I usually use 3500 to 4000 kbps average with an 8000 kbps max rate. I think DVD bit rate maxes out at 9500kbps but this also includes audio.

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[videobruger]

About specs

[Much2Learn]

Naturally the more you all tell me, the more questions I have; though these come out of curiosity, as you've answered my original questions!

So really, though the files average 1800 kbps bit rate, it has little to do with the bit rate of the authored DVD? In other words, the DVD having a bit rate double that of the original files still means some quality loss may result? Is that due largely to the difference between H.264 and MPEG-2?

[Southstorm]

Yes. Mpeg-2 and h.264 are two different compression methods. H.264 is more efficient, but does not meet the DVD specs.

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