Bitrate and Resolution.....how much is too much?

[jdogg2603]

Sorry if this has been covered, but I have been unable to get a clear understanding of this. When creating a DVD from a non-DVD compliant source file how do you pick the correct bitrate and resolution so as not to go completely overboard? In other words is there a point where higher bitrate or resolution doesn't get you better quality?

An Example
Source (tivo) = 1.5 hrs, 480x480, 3,500 kbps video, 192kbs audio, mpg2

Will this output:
6,500 kbps video (from bitrate calculator), 720x480

Be any better than:
3,500 kbps (original bitrate), 352x480 (dvd compliant resolution closest to source file)

Thanks a million for your advice.

[fritzi93]

Why don't you try a short clip each way?

That said, I'd do full rez. Your source bitrate is ample. Although half D1 is, as you say, closer, re-encoding it would entail some loss. SVCD rez is somewhat better than half D1. Here's the thing: Usually such questions turn on fitting the end product onto a DVDR5, with either good bitrate for half D1 or stingy bitrate for full D1. The bitrate you propose for full D1 (720x480) is more than adequate.

There is something else you could try. This might be an opportunity for you to experiment. Copy the file to another folder. Demux the MPEG. Upsample your audio with ffmpegGUI to 48kHz. Remux. Use DVDPatcher to patch the file. Author as usual and see if your set top player will play it. If you use TDA to author, it can make the audio compliant, so you could skip that step. Good luck.

[jdogg2603]

Thanks for the thoughts. A couple of points of calrification.

1) I did not realize file size was resolution dependent. The bitrate calculator here does not have an area for resolution.
2) You state that my bitrate is "more than ample" for full D1. That is sort of the crux of my question. Is there a way to determine what is exactly ample? ie Based on the original bitrate what is the minimum bitrate to use during the encodeing to prevent quality loss? The follow up questions to this answer are would this lower bitrate w/o quality loss be enough to reduce the encode time significantly and/or allow more video per disc.
3) The header patch does not work for my standalone.
4) I'll try a test of the two scenarios tonight.

Thanks again.

[gadgetguy]

Strictly speaking, filesize is only determined by bitrate and duration, but reduced resolution wil give better looking results at lower bitrates.
Click here for an explanation of the resolution / bitrate ratio.

[lenti_75]

Sorry if this has been covered, but I have been unable to get a clear understanding of this. When creating a DVD from a non-DVD compliant source file how do you pick the correct bitrate and resolution so as not to go completely overboard? In other words is there a point where higher bitrate or resolution doesn't get you better quality?

An Example
Source (tivo) = 1.5 hrs, 480x480, 3,500 kbps video, 192kbs audio, mpg2

Will this output:
6,500 kbps video (from bitrate calculator), 720x480

Be any better than:
3,500 kbps (original bitrate), 352x480 (dvd compliant resolution closest to source file)

Thanks a million for your advice.

6500 should look better, 3500 and half D1 IS dvd compliant, but that is usually for svcd mpeg1 files.
you resolution is already higher than that, so if going lower, you lower tha quality.

just do a test and see what happens.

[edDV]

I'm unfamilliar with the Tivo MPeg2 format. 480x480 is not DVD spec. If you want the file to be encoded at 704x480* at higher bitrate to preserve H resolution then do it (6,500 Kb/s to fit seems reasonable).

Or you can filter down the H resolution to 352x480 ~ 25% and use 3,500 Kb/s or lower.

* use 704x480 which matches 4:3 aspect ratio. 720x480 may add black edges left and right depending on the encoder.

[jdogg2603]

Strictly speaking, filesize is only determined by bitrate and duration, but reduced resolution wil give better looking results at lower bitrates.
Click here for an explanation of the resolution / bitrate ratio.

Thanks gadgetguy, that was exactly what I was looking for. The first disc I burned was at Half D1 with a VBR average of 6500. From the chart that was complete overkill. A VBR average of 3300 and max of 4200 would have been more appropriate.

[edDV]

Just as long as you realize you are tossing 25% of your horizontal resolution for 352x480, that is true.

As for going from 3.5 Mb/s CBR to VBR, I'm not sure if any re-encoding bitrate over 3.5 Mb/s has any benefit.