which scenario gives a higher quality video?

[graysky]

Source is a DAR=16:9, 720x480 DVD and the movie aspect ratio is 2.40:1. Since it has a DAR of 16:9, when I play the original VOB in mplayer, it gets prescaled to 854x480 since 480x(16/9) = 854.

If I crop out the black bars which are a total of 124 pixels, I'm left with a 720x356 video. Which of the two scenarios will give me a higher quality encode:

1) Encode to 720x352 with a 12:5 AR in mkvmerge. Result is mplayer prescales the 720x352 video up to 846x352.
2) Encode to 656x272 with no forced AR. Result is mplayer displays the video with no prescaling at 656x272.

I will encode this to take up 1/3 of a DVDR (1433 Mb) so the bitrates will be different, but both Qf values are over 0.3. I think option 1 should be higher in quality, but what effect does the the 720 --> 846 prescaling in the player have on the quality?

[DJRumpy]

I always leave the original DVD resolutions intact (sans the letterboxing of course). I find it looks better to my eyes with no resizing. Your basically encoding the source as-is. Just make sure you have sufficient bitrate for the higher resolution. I also overcrop to achieve mod16, rather than resizing. You lose a few pixels, but avoid resizing at all.

Go with option 1, and overcrop to achieve mod16.

You should also try wiping your MeGUI install. Something isn't right if it's not properly handling the SAR.

[graysky]

Overcrop, eh? So that means that when you take pixels off they come off in 16's? For example, there are blackbars on top and bottom. Instead of cropping 60 from the top and 64 from the bottom I crop 64 from the top and 64 from the bottom. That leaves me with 352 pixels now.

After that I *don't* add a line for resizing at all, rather I set the AR in mvkmerge? Is this correct?

2nd question: how do you determine if you have "sufficient bitrate"? I have been using the Qf method and shooting for 0.25-0.35 w/ x264.exe. How do you do it?

Thanks!

[DJRumpy]

1st Question: Correct. It will auto-crop to the nearest 16. You don't have to resize at all using the overcrop method.

2nd Question: Sufficient bitrate is all subjective. Poor options with higher bitrate will still give you a crap encode. I use between 800-1000 kbps for dvd resolution video's (2.35-1.77), with maxed out options for motion detection and such. Depending on the source's noise, sometimes I may bump it up as needed. It's a good ballpark to start with though. A clean source (digital film) will look great with 800 kbps, while an older analog dvd will look like pretty bad in most cases. You'll need to find bitrates that are acceptable to your eyes. The aspect of the movie also affects the bitrate requirements, as you have more image area to encode with full screen sources as opposed to wider aspect sources.

Try one at 800 kbps with maxed motion detection and ref frames and see how you like it. You'll need a dual core, as it takes impossibly long on an older processor.

[jagabo]

I usually encode with constant quality (target quantizer, constant quantizer, the name varies depending on the codec). That way I always get the quality I want. The file turns out whatever size is necessary for that quality.

[graysky]

Thanks again for the info. I have been using the HQ-Slow profile in MeGUI for x264.exe and I usually set the size to be 1/3 DVDr. Bitrates vary with time obviously but usually are over 1000 easily.

What do you recommend for profiles or do you not use x264 at all?

[DJRumpy]

I use the CE-HighProfile as the default.

Main Tab ----------------------
Turbo Enabled (automated 2-Pass)
Bitrates set to 800-1000 depending on source aspect and source quality

RC and ME Tab ---------------
Chroma M.E.: Checked
M.E. Range: 16
M.E. Algorithm: Exhaustive (Multi-Hex is ok)
Subpixel Refinement: 6 or 7
Number of Ref Frames: I leave this at 3..don't go over 5 as your just wasting your time for little gain. Also slows down the encode the higher you go...
No Dct Decimation: Checked
No Fast P-Skip: Checked
I enabled all of the Macroblock Options on the Advanced TAB.
Number of B-frames: 3

CQ Mode is OK, but I find the multipass VBR modes to produce better quality at a lower bitrate. CQ will give you decent quality but at the cost of unecessary filesize. I have over 400 DVD's so space becomes somewhat of a premium as time goes by. Most encodes come out to just under a gig for a standard length movie.

[graysky]

Cool man, thanks again. Last question deals with audio. I found that if I downmix 5.1 --> stereo from within MeGUI the resulting file is too quite (true for aac or ogg). The workaround I found is to downmix in foobar with its DSP plugin and either output to wav and then compress with oggenc2 or with neroacc. How do you handle you audio streams and do you notice this decrease in volume I'm talking about?

Thanks again!

[jagabo]

DJRumpy and I have discussed this before. He thinks there's a difference in quality between single pass CQ and multipass VBR at the same size. I think there's no significant difference. Try it and decide for yourself. Even if you decide CQ requires slightly higher bitrate, it has the advantages of always delivering the quality you ask for and it's twice as fast as a 2-pass VBR encode.

Re AC3 conversion volume: turn up the gain on your AC3 decoder.

[DJRumpy]

I just leave the audio as is in regards to channels. Use the Nero Digital profile (download the files from Nero's site..just goole them). Any tuner worth it's weight can downmix the audio for you on playback. I enable the following:

Output Channels: Keep Original Channels
Improve Accuracy using 32bit & Float compuations
Adaptive Bitrate@ 128 kbit/s
AAC Profile: HE-AAC

You can try the "Increase Volume automatically", but I wasn't particularly pleased with the output. It's been a while since I tried it though.

jagabo, CQ doesn't have the advantage of multi-pass, and is inherently of lesser quality as a result. The only time it would offer the same quality as multipass is if the Quantizer settings were set to the point where there was a 1:1 copy or the settings were set high enough to compensate for the bitrate gained from multiple passes. There is a reason every encoder out there offers multipass. You pay for the quality with time. That said, the first pass in MeGUI takes only 30 mins or so on my mediapc. This is not a situation like you used to see with CCE, or TMPGenc where each pass always took the same amount of time. The first pass goes quickly and doesn't add significantly to the encode time IMHO. Of course that will vary based on the hardware x264 is not friendly with old hardware..lol

[jagabo]

One other thing you might consider about using DAR rather than square pixels with your encodes: not all players support DAR. In the future, if you get a set-top player that will play your files (I don't know any that support h.264 decoding at this time), it may not pay any attention to the DAR. For example, many set-top Divx/DVD players don't support DAR at this time.

[DJRumpy]

I always encode with an embedded SAR. I use Media Player classic which does obey the embedded SAR. Saves bits, and allows you to skip resizing the source and losing quality as a result.

[graysky]

yeah, mpc rocks as does mplayer

[jagabo]

I usually use MPC too.

[DJRumpy]

One would think MS would finally get the hint and tone down that Bloatware they call a media player

[bullet_ballet]

It's an old thread, but my questions really fit in here. If the actual res is smaller than the DVD res (4:3 dvd, for instance) is it better to just resize or should I stick with avoiding a resize and doing an anamorphic encode?

Also, why is a mod16 resolution required? Will MeGUI refuse to encode if it's not mod16?

[DJRumpy]

I always do anamorphic encodes when applicable. MEGUI will warn that using anything that isn't MOD16 will likely result in problems in playback, but it will still encode it. Anything that isn't divisible by 16 should be avoided.

[jagabo]

The problem with non square pixel encoding is that some players don't respect the aspect ratio setting. This is especially problematic for Divx encoding for set-top Divx/DVD players.

[DJRumpy]

Encoding for set top Divx/DVD players wasn't stated in the question jagabo. Neither was encoding for a player that doesn't respect DAR flags in a DivX/XviD encoding. Since he specifically asked about using DAR flags, then one would have to expect that his player (hardware or software) supports them.

[jagabo]

Encoding for set top Divx/DVD players wasn't stated in the question jagabo. Neither was encoding for a player that doesn't respect DAR flags in a DivX/XviD encoding.

No duh.

Since he specifically asked about using DAR flags, then one would have to expect that his player (hardware or software) supports them.

What about his next player? I wasn't telling the OP he should or shouldn't use square pixels. I was simply pointing out that there were possible issues with DAR flags -- in case he wasn't aware.