Encoding Setting For 720p help please?

Jan 19, 2011 at 9:56 PM

Hi,

I am using this program with great success, I just need some help with getting it right for 720p please?

I can successfully encode from a blu-ray using constant quality 18-20 & copying the audio streams untouched & reducing the resolution to 1280X720 & am getting fantastic results.....except the file sizes are around 6gb.  I have several NPW XVID 720p releases that I downloaded as it is easier than backing up my blu-rays & they are around the 2.5gb size & the quality is absolutely superb and no different to the quality I am getting from my encodes using Vidcoder.  Can anyone please help?

 

Many Thanks In Advance!

Jan 19, 2011 at 10:10 PM

 to get that file size choose average bitrate 3000 and choose 2 pass

Coordinator
Jan 19, 2011 at 10:43 PM

The first question is the audio. How many channels are on the other file? Is it compressed? Compressed audio can sound basically identical to the raw Blu-ray audio, especially if you're testing on a 2-speaker setup and one of the audio tracks has been downmixed to 2 channels. Anyway, the audio might be part of the difference here.

Then there's the video. There are two popular ways to do it:

1) Pick a file size or bitrate. The encoder does one pass to find out what quality to target. For simple, low-motion videos, you'll get high quality. For complex, high-motion videos, you'll get lower quality.
2) Pick a quality target. The encoder will use whatever data necessary to make the video meet the quality you specified. So every video you encode will have the same consistent quality, but the file sizes can vary.

I prefer #2, picking the quality target. That's why all of HandBrake and VidCoder's presets use it. It lets you save space on simple videos, rather than just throwing extra unneeded data at it, and have nice looking complex, high-motion videos. Plus, the encode is faster since you only need one pass. The only advantage that #1 has is that you always know what the file size will be for a video of a given length. Unless you need to burn it to a CD or DVD (which is rarer and rarer these days), it's not very useful.

What I suggest you do is fiddle around with the quality target until you get a good quality/size mix. Good values are around 18 (high quality) to 25 (low quality). You can use the preview window or just encode 15-second segments or something. x264 is the best video encoder in the world, so for any size, it should look the best, and any video quality it should have the lowest file size.

So in short, you may be able to target a lower quality without noticing the difference (and thus get a lower file size).

Also it helps to use the x264 settings from the High Profile preset: this uses all the bells and whistles in H.264 to efficiently encode good looking video.

Jan 22, 2011 at 9:31 AM

Hi,

 

Thank you so much for your detailed replies!

 

As I stated in my original question I am copying the audio streams untouched as sound is very important to me (as is video)

Like you RandomEngy I prefer to pick the quality target, but I am getting such wildly varied results.... I have selected the high quality profile, changed the resolution output to 1280X720 & set the quality to 20.  Below is a list of my results...

A Bugs Life 2GB

Ghostbusters 5.9GB

The Green Mile 5.2GB

28 Days Later 2.2GB

 

I am really aiming for between 2-3.5GB per movie (As are the NPW Xvid Encodes) but if I change the quality from 20 to say 25 to get those file sizes I am really able to notice the quality reduction..

Am I missing something?

 

Many Thanks again...

Coordinator
Jan 22, 2011 at 4:46 PM

Well yes, sound is important but it's still quite possible to compress sound without it sounding any different afterward. And if your baseline videos are compressing the sound, or they have fewer channels, then you're not making a fair comparison of the video sizes.

Once you factor out the audio you can make comparisons. Once you've factored that out and you think you've got an example of a lower quality video with higher size than your XVID encodes, then something might be wrong. But from what you've told me this seems in the realm of plausibility. The Green Mile is really long so it doesn't surprise me that it's big. Ghostbusters might have a lot of grain that adds to the complexity of the pictures. Animation typically compresses quite well for any given quality level.

Feb 5, 2011 at 11:15 AM

Hi,

I haven't had a great deal of time to play with this, but I have now & also overclocked my Quad Core to 4X4.1Ghz which has halved my encoding time!!!!!! :-)

You were absolutely right about the audio, I found that NPW encode's were using 640 kbps & I am starting to now get somewhere close to his filesizes which is great, I am using Constant Quality 21 & 640 kbps 5.1 sound.  I have the following questions if you can help me please?

When I choose AC3 Sound on Vidcoder I only have the option for 6 channel (discrete) : What does the discrete part mean? I do get DD5.1 when I choose this but what is discrete?

This is my biggest question... How do I know that I am getting the correct resolution?  if I choose to keep aspect ratio I get some strange resolutions.. For example

I am using the movie 300 for this

Source File 1920 X 1080

If I change it to 1280, Vidcoder automatically select 440 so I end up with 1280 X 440 & even on a 50" Plasma this looks VERY letterbox.  Now if I compare that to the NPW Xvid Encode he has 1280 X 536! which looks perfect.  So how would he/I come to choose that resolution? basically how to I work it out?

Many Many Thanks again for a fantastic program, I really am loving it but need to understand more...

Coordinator
Feb 5, 2011 at 6:13 PM

You say that when you choose AC3, 6 channel is your only option? The dropdown won't let you choose anything else? That shouldn't be the case. Do you have a screenshot?

Anyway I think what the 6 channel discrete thing means is that each audio channel is kept separate, for "true" 5.1 surround. Dolby Pro Logic II and the others I believe mix down to fewer channels.

As for it choosing the aspect ratio, what picture settings are you using? Anamorphic? What's the input and output look like on the Picture tab (including Pixel Aspect Ratio)? It could be that VidCoder is not doing the automatic resolution calculation correctly but I'd need to know the specifics.

Feb 6, 2011 at 5:08 PM

Hi,

Sorry I meant that 6 Channel (discrete) was my only option for 6 Channel sound, there are other 2 channel options but I obviously don't want those. I was basically trying to say that there was no other 6 channel options without discrete....

 

As for the aspect ratio I just have keep aspect ratio ticked & have anamorphic as none, then when I type the width it automatically gives me the height, but as I said 1280X440 is far to small

If I select anamorphic loose, & then type 1280 it automatically selects 1280X528 so I suppose that is alot closer so maybe that is the option I should be using?

 

All I am trying to do is convert my Blu-Ray Disks into 720p with the best possible picture settings & file sizes around 2-5 to 3gb

 

Thanks again for your quick response I really appreciate it!

Coordinator
Feb 6, 2011 at 5:26 PM

What I'm asking is what do the Input and Output boxes say on the Picture tab? Including the Pixel Aspect Ratio. The info in the blue and green boxes. If it's picking the wrong dimensions that's a bug. But yes, you can use one of the other anamorphic modes to fix it as well. What may also work is leaving the height blank, and it should figure it out automatically.

Feb 6, 2011 at 7:11 PM

Hi,

The input box says

1920X1080

1.00 (1/1)

1920X1080

 

If I select Loose Anamorphic & keep aspect ratio I get the following in the output box

1280 x 528

99/100

1267 x 528

 

What is the difference between Storage & Display Resolution?

 

Cheers Mate

Coordinator
Feb 6, 2011 at 9:33 PM

Alright. Found the bug and fixed it. Should show up in the next version.

Storage resolution is how the video is stored: how many pixels wide and tall. But it doesn't necessarily need to be displayed that way. There can be information in the video to tell it to change the aspect ratio when played back. That modified resolution is a display resolution.

Feb 6, 2011 at 11:14 PM

Thats Cool...Thank You... should I hold off starting all my Blu-Ray's until you release the fix?

 

Cheers

Coordinator
Feb 7, 2011 at 4:42 AM

You can start now if you want. For instance you could just leave the height blank and it should work.

Coordinator
Feb 26, 2011 at 11:25 PM

Alright, fix should be in the freshly released 0.8.2.