What are P , I and B frames ?

[PrinceSwaraj]

Hello VH ....................


I wanted to ask what are :
#1. P Frames
#2. I Frames
#3. R Frames


Please tell in simple words , in which I can understand ...
and the ideal values for each of'em !

THANK YOU !!

[Kerry56]

Try the Wikipedia article to get a basic understanding: http://en.wikipedia.org/wiki/Video_compression_picture_types

[DB83]

You can not get this in more simple words than the wiki article

"An I‑frame is an 'Intra-coded picture', in effect a fully specified picture, like a conventional static image file. P‑frames and B‑frames hold only part of the image information, so they need less space to store than an I‑frame and thus improve video compression rates.

A P‑frame ('Predicted picture') holds only the changes in the image from the previous frame. For example, in a scene where a car moves across a stationary background, only the car's movements need to be encoded. The encoder does not need to store the unchanging background pixels in the P‑frame, thus saving space. P‑frames are also known as delta‑frames.

A B‑frame ('Bi-predictive picture') saves even more space by using differences between the current frame and both the preceding and following frames to specify its content."

Do not worry about ideal values. Only experts mess around with those. Stick to the preset ones according to the codec you use.

[PrinceSwaraj]

You can not get this in more simple words than the wiki article

"An I‑frame is an 'Intra-coded picture', in effect a fully specified picture, like a conventional static image file. P‑frames and B‑frames hold only part of the image information, so they need less space to store than an I‑frame and thus improve video compression rates.

A P‑frame ('Predicted picture') holds only the changes in the image from the previous frame. For example, in a scene where a car moves across a stationary background, only the car's movements need to be encoded. The encoder does not need to store the unchanging background pixels in the P‑frame, thus saving space. P‑frames are also known as delta‑frames.

A B‑frame ('Bi-predictive picture') saves even more space by using differences between the current frame and both the preceding and following frames to specify its content."

Do not worry about ideal values. Only experts mess around with those. Stick to the preset ones according to the codec you use.

Thanks friend .........
But I really need those values !
PLEASE !

[usually_quiet]

If you have to ask what I-frame are, you don't need the "ideal values" for I, B, and P frames. What you really need is newbie-friendly software that doesn't ask you to input values for I, P, and B frames.

How could anyone even answer this question? You haven't even given us any information about what video format/codec you are using or the software you are using.

[Hoser Rob]

+1 to the above. If you don't even know how to ask the question you won't get a coherent answer.

There is no simple explanation of video encoding. It's complex. That's all there is to it. They didn't design those format standards for noobs who want to rip and compress their dvds. They are professional standards and designed for professionals.

[PrinceSwaraj]

I am talking about x264 codec ......
Software : MeGUI

[jagabo]

And there are no ideal values. Just different compromises.

[usually_quiet]

I am talking about x264 codec ......
Software : MeGUI

Well, MeGUI itself doesn't ask for that information, x264 does. There is a tutorial about MeGUI's more advanced features here You might as well start with that. There is no recipe that can produce an ideal encode for every video file someone wants to convert. Otherwise there would be an identical preset for it in every converter. You will need to experiment with different settings and come up with your own profiles.

I don't use MeGUI. I mostly work with MPEG-2 video, and I decided early on to make it my mission in life to avoid re-encoding my video files whenever possible. So don't expect more help from me.

[LigH.de]

As long as you don't really know about the basics of video encoding, you better don't try to change advanced parameters.

Just rely on the basic encoder setup: Preset (speed vs. thoroughness), tuning (for specific content), maybe device compatibility (if not played on a PC only); and either a target bitrate (2-pass VBR) if you have to fill up a medium with tight capacity, or a quality preservation value (1-pass CRF) otherwise.

[pandy]

But I really need those values !
PLEASE !

What do you need? - i'm reading this topic, seem everything was provided. So what kind of values you asking for and perhaps it will be easier if you share your problem or what are you trying to do.

[LigH.de]

I could only imagine I:P:B ratios in GOPs or similar. As already said: Really "advanced" options, do not change unless you understand them as good as the x264 developers.

[pandy]

I could only imagine I:P:B ratios in GOPs or similar. As already said: Really "advanced" options, do not change unless you understand them as good as the x264 developers.

So this mean that he need to go for 2 pass and manually set picture types (so he need to use tool to manipulate x264 stats file http://mewiki.project357.com/wiki/X264_Stats_File ).

[LigH.de]

I did not even mean this. Just --ipratio (default: P frames quantizer is 1.4× as big as I frames quantizer) and --pbratio (default: B frames quantizer is 1.3× as big as P frames quantizer).

[pandy]

I did not even mean this. Just --ipratio (default: P frames quantizer is 1.4× as big as I frames quantizer) and --pbratio (default: B frames quantizer is 1.3× as big as P frames quantizer).

So this is just different quantizer used for I, P, B frames but not distribution (not directly as indirectly it should affect in limited way also frame type distribution).

But honestly - this shows that OP need to explain why he ask - best provide information what he trying to achieve - perhaps there is way better method to this (i have only one idea why he ask about such things - synthetic video with particular frame type distribution to test some functionality of some product)

[hello_hello]

I am talking about x264 codec ......
Software : MeGUI

Well, MeGUI itself doesn't ask for that information, x264 does. There is a tutorial about MeGUI's more advanced features here You might as well start with that.

I wouldn't. It's quite out of date. It discusses using the old x264 encoder presets which aren't automatically included any more and are in fact probably a bad idea, as they're designed for older x264 versions....... back before --bluray-compat was even a command line option.
The encoder configuration now has a drop down list of standalone devices you can select for compatibility.

Some of the advice even seems a little odd to me. Like choosing the VerySlow x264 preset then recommending settings which don't conform to the VerySlow preset. 2 pass encoding is recommended over quality based encoding.

I don't use MeGUI. I mostly work with MPEG-2 video, and I decided early on to make it my mission in life to avoid re-encoding my video files whenever possible. So don't expect more help from me.

I'm sure PrinceSwaraj will be devastated........ and expecting help with video conversion in a sub-forum entitled "Video Conversion", dedicated to topics involving converting video..... what are people thinking???

PrinceSwaraj,
When it comes to configuring the x264 encoder using MeGUI, open the encoder configuration and use the "load defaults" button.
- Select your desired quality. The default is 23. Lower values = higher quality = larger file sizes. I mostly use CRF (quality) 18 myself, but it's personal preference.
- If you want to, select a target playback device in the dropdown list. If you don't need to, either leave it set to "Default" or change it to "DXVA". The most commonly supported Profile and Level in hardware players today is probably High Profile, Level 4.1, and selecting "DXVA" does nothing more than set High Profile, Level 4.1. If you leave the target playback device option set to "Default", the encoder will pick an appropriate profile and level. That's fine.
- Select an appropriate Tuning from the drop down list. Most of the time you'd probably want to use "Film" but choose another if it's appropriate.
- The default speed preset is "Medium". It's fine to use, but for slightly better compression you can choose a slower one. Pick the slowest speed preset you can stand.

That's it. Don't mess around with x264's advanced settings unless you really know what you're doing.
The presets are simply different combinations of x264's advanced settings. As an example, if you select Tuning "None" in the main x264 configuration tab, then switch to the "Frame Type" tab. Look at the Deblocking values. They'll be zero and zero. Change the Tuning to "Film". Look at the DeBlocking values again and they'll be -1 and -1.
The speed presets change some of the settings for B frames and reference frames etc in a similar manner. Use the speed presets and tunings. If the quality isn't as high as you'd like, lower the CRF (quality) value. Unless you know what you're doing, changing the advanced settings might have an adverse effect on quality.

Edit: In order to see the advanced x264 settings in MeGUI's encoder configuration you need to check the "show advanced settings" option. New tabs will appear under which you'll find the advanced x264 settings.

[usually_quiet]

Once in a while I do re-encode HD MPEG-2 for a DVD conversion smart ass. If the OP had asked about that, I might have given better advice. Nobody else even bothered to post a tutorial, even an old one.

Well now that an "expert" has appeared this newbie is bound to get all his questions answered in complete detail. I know you never loose your temper with newbies who are not inclined to take your advice. Have fun.