Encoding quality with QuEnc

[cd090580]

Hi,

I'm creating a dvd slide show with dvdslideshow gui. All is now working great.

But I have a question about the quality.

For each slide I put a duration of 8 seconds. I noticed that the picture quality decrease with time and then go back to is full quality (that appears about each seconds like when a new gop is created).

Is it possible to fix that (keep same picture quality during the 8 seconds) ??

I disabled 2 pass and High Quality (too slow to encode) in quenc for the test. Does the picture quality will be the same during the 8 seconds if I check both options ?

If not, how can I keep the same picture quality during the 8 seconds for each slide ?

Thanks.

[gadgetguy]

Not much to go on. What resolution is the source? What settings are you using? What bitrates? You disabled 2 pass & HQ for the test of what? Are you using CBR or VBR? Mpeg2 or Mpeg1? Details, man details.

[cd090580]

The source are photos in 4-6 megapixels.
The target bitrate is 8500 kbps VBR in MPEG-2 for DVD.

I disabled 2 Pass & HQ to reduce the encoding time for some tests (encoding at 3 fps).

[gadgetguy]

The source are photos in 4-6 megapixels.

Those are probably high resolution photos requiring significant alteration to match DVD spec. But I ask again, what is the source resolution?

The target bitrate is 8500 kbps VBR in MPEG-2 for DVD.

Since you are so close to the max bitrate you will get very little benefit from doing 2 pass, VBR.

I disabled 2 Pass & HQ to reduce the encoding time for some tests (encoding at 3 fps).

Does that mean you were testing to see how much quality is sacrificed for a way to speed up encoding time or just to see if disabling will speed things up? Was the encoding at 3 fps before or after disabling HQ? Can I assume dvdslideshow frameserves? 3 fps is extremely slow but I suspect it has more to do with the alterations being done by dvdslideshow than QuEnc. It might be faster if you can save to a lightly compressed interim file (like DV-AVI or Huffy) and then encoding that file in QuEnc. Usually, for me, QuEnc encodes at somewhere between 13 - 15 fps depending on the source, the target bitrate, and the amount of filtering I'm doing in AviSynth.

[mats.hogberg]

Also, static images don't benefit much (if any) from VBR.

/Mats

[gadgetguy]

Also, static images don't benefit much (if any) from VBR.

/Mats

While that's true for a single still image, some images require more bitrate than others. A mostly dark image of a young girl lighting a candle would require much less than an outdoor kids party with many bright and different colors. So VBR could be beneficial for a slideshow if the difference between min/avg/max is adequate to be able to create a perceptable difference.