Bitrate of avi file and x264 file

[maass]

Hi all,

i converted one avi file of 1280x720 into x264 using Xvid4PSP.
i used the settings as Video encoding Q18 Extreme.
the original bitrate of avi file was 2150 and it changed to 5450 in x264.

now it may look a dumb question but what is the reason for such huge change of bitrate.
what is the advantage if the bitrate is high.

please anyone enlighten me on this.

thanks

[guns1inger]

Q18 Extreme means give me something that is pretty much identical in quality to the source. Every time you encode with a lossy encoder, you throw away some of the data, and consequently reduce the quality. The less data you throw away, the lower the loss. because you are talking about lossy codecs, in order to get identical quality to the source, you usually have to use a higher bitrate than the source.

Was this necessary in this particular case ? Probably not. I suspect you could have got the same quality from either a Q21 Ultra, or even a 2-pass encode with a bitrate of 2150 (assuming your AVI was an Xvid/Divx encoded file).

[maass]

Thanks guns1inger

thats some useful information.

and what if the case is a DVD.

one of my DVDs bitrate is at 4376 and to get a resolution of 1280x720 i tried Q21 Extreme and switched the bitrate to 3750 so that the file size is 4450Mb which i can fit in DVD.

i don't hardly find any change but is there any problem if i lower the bitrate to less value than it is.

and another small query regarding the Xvid4PSP.is there any user guide of Xvid4PSP which briefly says all the codecs information.

thanks

[guns1inger]

If it is a DVD, why bother trying to resize it up to 720p. Keep it as SD resolution and let your TV or player upscale it. Chances are the results will be far better, and you can probably fit 2 movies to a disc.

[jagabo]

When using constant quality encoding many things will effect the final average bitrate. Bigger frames, more detail, more action, more noise, higher contrast frames, higher frame rates -- all these things require more bitrate.

In general, h.264 requires less bitrate than MPEG2 or Divx/Xvid. But if you specify a very high quality level the encoder will work very hard to preserve all the little defects created by Divx/Xvid/MPEG2 encoding (because it can't tell which are real details and which defects), without adding more defects itself. So it's possible to end up with a higher bitrate than the source.

[maass]

Thanks guns1inger and jagabo ...

well i installed Xvid4PSP in one of my friends system and i am getting the error (attached)

can anyone suggest what is the problem

[MysticE]

https://forum.videohelp.com/topic360584.html

[maass]

thanks mystice...the problem is solved

and regarding the deinterlace option of Xvid4PSP what should i use...

i have some regional DVDs which are to be deinterlaced...i see horizontal lines when i decode the DVDs to mkv file..

thanks

[jagabo]

What deinterlacing options does Xvid4PSP have to select from?

Deinterlacing can be a very complex issue. Without seeing a sample of your source it will be hard to say which option to choose.