Encoding my DVDs to x264 - what is the minimum bit rate for 1080p ?

[Kamui]

Hi folks,

I am going to build a HTPC and hook it up to a 1080P display (yet to be purchased...) . Can anybody tell me what is the least acceptable bit rate (in X264) that I should encode my Dvds in order to maximize the quality of the output?

I know that most dvds nowadays are in 720x480 resolution. When I encode with FairUse, I use the x264 codec and I set the output file to 720x304 resolution, the bit/pixel to 0.25 and compression to 96:1.

Thanks,

K

 

[SynthDude2001]

I only have limited experience with x264, but I've had pretty good results encoding some 720p source material at 3000kbps...differences from the original are small. If you're encoding lower resolution DVD source, I would imagine that a bitrate in that range should be quite sufficient to minimize any encoding artifacts and the like.

 

[Kamui]

hi synth, that means that your output file is 1280x720 right? Just a quesiton... given that most of the dvds come in 720x480, doesnt that stretch the image?

 

[JAG87]

first of all, I hope you are talking about h.264

second of all, would you not want to rescale your movies to 1920x1080? why would you make them 720x304... you know how brutal they are going to look like on a 1080 display? Even thou the scaler on your video card is good, they are still going to look brutal. If you dont want to rescale (I understand CPU wise it will be a killer with h.264) at least keep the original resolution. A good move would be to rescale to 960x540 (hopefully youre going to use a Lanczos filter not that bilinear bicubic $hit). This way the scaler will have to do 1:4 job, which is nice and clean. 540p should not be too hard on your cpu either.

bit rate wise, I see you are choosing a 96:1 compression... would that not automatically tell the codec which bitrate to use... anyways, it all depends on the space you have available for storage. Ideally with h.264 you should not tell much of a difference above 2000 kbps. At that point there is enough bitrate to handle all scenes well. Of course, if you are encoding some love story movie with mostly still scenes, you can even use less then that, but if you are encoding a fast scene changing movie, you might want to be more generous with the bitrate. in general think about it this way, h.264 is 4 times better then mpeg2, so you need 1/4 of the bitrate in h.264 to get the same quality as mpeg2. so 2mbps in h.264 = 8mpbs in mpeg2, which is the maximum bitrate for DVDs. This way you are completely eliminating the possibility of loosing any detail present in the original mpeg2 movie.


thats a quick summary for you, read this guide if you want to know more
http://www.pixeltools.com/h264_paper.html

 

[SynthDude2001]

Originally posted by: Kamui
hi synth, that means that your output file is 1280x720 right? Just a quesiton... given that most of the dvds come in 720x480, doesnt that stretch the image?

Yes, the output file is 1280x720...I'm not talking about DVD's in my case, I'm actually recording and encoding 1280x720 broadcast HDTV. There wouldn't be much point in upscaling DVD's to a higher resolution and then encoding that. I'm just saying, since 3000kbps works pretty well for 720p HDTV (at least in my experience), it should be more than sufficient to retain a great picture for DVD-resolution source material.

 

[Kamui]

Jag,
thanks for the excellent advice. I should have asked the forums before encoding some of my dvds...now I need to go back. OH well, it is no biggy.

Also, is there a tool that you could recommend to check the average bitrate of my dvds?

 

[Gooberlx2]

Originally posted by: JAG87
why would you make them 720x304... you know how brutal they are going to look like on a 1080 display? .........at least keep the original resolution.

At first I was thinking maybe he was chopping out the letterboxing bars....but then even 720x304 isn't 16:9. I can't imagine why one would output to that resolution.

 

[Kamui]

actually goober,

I left the horizontal scale the same at 720... but chopped the black area of the movie off. That is how I got the 720x304. Is that abnormal?

 

[JAG87]

its not abnormal, but it sure is pointless because your gonna get those black bars anyway on your display since a 720x304 picture cannot fill a 16:9 display. stick to widescreen resolutions, otherwise you will make rescaling even harder then picture even worse. if you are planning 1080p display my advice is either arm yourself with a massive hard drive and a powerful cpu and go 1080, or rescale everything to 540.

a tool to check the bitrate? powerdvd does that... play the dvd, right click on the screen and click Show Information...

 

[ProviaFan]

Originally posted by: JAG87
its not abnormal, but it sure is pointless because your gonna get those black bars anyway on your display since a 720x304 picture cannot fill a 16:9 display. stick to widescreen resolutions, otherwise you will make rescaling even harder then picture even worse. if you are planning 1080p display my advice is either arm yourself with a massive hard drive and a powerful cpu and go 1080, or rescale everything to 540.

Ok, I don't quite understand... if the original movie was ripped from the DVD with black bars on the top and bottom, when recompressed the black bars will compress somewhat, but wouldn't it be even better just to crop the video so the data doesn't even have to be bothered with from the start? It's not going to change anything about the rescaling, since the video will be rescaled by the same amount, which is determined by the width that must be multiplied by a factor that doesn't change regardless of whether the vertical part has been cropped - right?

 

[Kamui]

ok Jag, in fairuse, when I state I want 96:1 compression, how do I determine the bitrate rate that I am seeking to encode at?

 

[Stoneburner]

what's the point of resizing higher? I dont think it can look better than the source. At least not from all the attempts i've made.

 

[Kamui]

*bump

 

[Howard]

Originally posted by: Stoneburner
what's the point of resizing higher? I dont think it can look better than the source. At least not from all the attempts i've made.

qft

 

[Kamui]

qft?

 

[ProviaFan]

Originally posted by: Kamui
qft?

Quoted For Truth (usually)
Quit F$%&ing Talking (only in OT/P&N)

 

[dug777]

quoted for truth

 

[JAG87]

resizing does not make the source material look better, but it helps on large displays with large pixel matrices. If you have 100 inches of screen, a movie at 480p will look ok, but if you take that movie and rescale it to 1080p, although it wont add more detail to the picture it will still look better because of the pixel pitch factor. 720x480 will have massive gaps between pixels, while 1920x1080 will show the same detail but with interpolated gaps (gaps are filled with the average of the nearby pixels).

do you understand?

 

[JAG87]

Originally posted by: Kamui
ok Jag, in fairuse, when I state I want 96:1 compression, how do I determine the bitrate rate that I am seeking to encode at?

i have no idea ive never used that program.

 

[Wreckage]

Originally posted by: JAG87
second of all, would you not want to rescale your movies to 1920x1080?

How many minutes of that would you get on a DVD?

 

[rbV5]

resizing does not make the source material look better, but it helps on large displays with large pixel matrices. If you have 100 inches of screen, a movie at 480p will look ok, but if you take that movie and rescale it to 1080p, although it wont add more detail to the picture it will still look better because of the pixel pitch factor. 720x480 will have massive gaps between pixels, while 1920x1080 will show the same detail but with interpolated gaps (gaps are filled with the average of the nearby pixels).

The scaler on your graphics hardware is(should be) far superior than to trying to upscale-resize while encoding video. Its a huge waste of CPU, storage and personal time that almost guarantees worse PQ rather than improving it in any possible way.

Repeat: You do not want to rely on some lossy codec's resize algorithm to upscale your video during the encoding process, thats your graphics hardware's job.

 

[JAG87]

Originally posted by: rbV5

resizing does not make the source material look better, but it helps on large displays with large pixel matrices. If you have 100 inches of screen, a movie at 480p will look ok, but if you take that movie and rescale it to 1080p, although it wont add more detail to the picture it will still look better because of the pixel pitch factor. 720x480 will have massive gaps between pixels, while 1920x1080 will show the same detail but with interpolated gaps (gaps are filled with the average of the nearby pixels).

The scaler on your graphics hardware is(should be) far superior than to trying to upscale-resize while encoding video. Its a huge waste of CPU, storage and personal time that almost guarantees worse PQ rather than improving it in any possible way.

Repeat: You do not want to rely on some lossy codec's resize algorithm to upscale your video during the encoding process, thats your graphics hardware's job.

or that...

 

[Kamui]

ok. tahnks for all the input guys. I decided to do some more trial and error to determine what is the best output thanks all

 

[b0mbrman]

So what did you decide?

 

[gsellis]

Originally posted by: rbV5

resizing does not make the source material look better, but it helps on large displays with large pixel matrices. If you have 100 inches of screen, a movie at 480p will look ok, but if you take that movie and rescale it to 1080p, although it wont add more detail to the picture it will still look better because of the pixel pitch factor. 720x480 will have massive gaps between pixels, while 1920x1080 will show the same detail but with interpolated gaps (gaps are filled with the average of the nearby pixels).

The scaler on your graphics hardware is(should be) far superior than to trying to upscale-resize while encoding video. Its a huge waste of CPU, storage and personal time that almost guarantees worse PQ rather than improving it in any possible way.

Repeat: You do not want to rely on some lossy codec's resize algorithm to upscale your video during the encoding process, thats your graphics hardware's job.

Now that we are on the same page...

QFT

Trying to take 480i to 1080p in a codec will introduce a lot of artifacts.