Best bitrrate for HD

[supercain]

Hi,

i have a 23min long video that has 1920x1080 resolution and is 1.5GB in size with a bitrate of 9730kpbs. I want to compress it on virtualdub using the x264 codec in order to keep the highest quality (HD) and make it as small as possible. What bitrate should i use to compress?

Thank you.

[yoda313]

Use a bitrate calculator to determine that.

But don't go really low. It will lose quality the lower you go.

We really can't give you a hard and fast number as that is really up to each individual. Video is kind of an art more than a science in that regard. We can't say use bitrate x in every situation to get the best result. Its like telling a painter to only use a certain shade of blue because thats the "best" blue to use. It varies.

What I would recommend is doing a test encode with a shorter video with the same specs (or use the cut feature in virtualdub to only encode a minute or two of the video to test the bitrates you want to use). THat way you keep the original video but get test samples to use.

[jagabo]

Any recompression with a lossy codec will reduce quality. So what you have already is the highest quality possible (starting with that source). If you want to make the file smaller what's "best" is a matter of compromise. That's a matter of personal taste and it will vary with every video (some video is more "compressible" than others). So nobody can answer that question for you.

[supercain]

Hmm i see. Thanks. Well, then lets say its you instead of me. What bitrate would you use?

[jagabo]

I don't use bitrate based encoding unless I need a specific file size (for example with MPEG 2 encoding for DVD where you want to fill the disc). I normally use constant quality encoding, CRF in x264. Usually CRF=18.

[manono]

Hmm i see. Thanks. Well, then lets say its you instead of me. What bitrate would you use?

I don't think any of us would do a bitrate-based encode given those restrictions. We'd do 1-pass quality-based encodes for the quality we're satisfied with.

But even if doing 2-pass bitrate-based encodes there's still no way at all to answer your question. Maybe try and digest what jagabo said a little better. some video is more "compressible" than others

[jagabo]

Here are some examples using Xvid (a different codec but similar issues):

https://forum.videohelp.com/threads/295672-A-problem-for-video-experts?p=1811057&viewfu...=1#post1811057

One of the video required 400 kbps to look good, the other 8000 kbps. If someone told you 2000 kbps was the best bitrate for Xvid encoding, and you encoded all your videos at that bitrate, you would end up wasting space on the "clean" video. The "noise" video would look poor. Real movies usually don't vary so widely but they do vary. So there's no best bitrate for all movies.

Encode some representative clips at different CRF values. Decide what quality you're happy with. Then encode all your movies at that CRF. I usually use CRF=18. But sometimes I might want a particular movie to look even better so I use a lower CRF. Sometimes I don't care much about the picture quality so I'll use a higher CRF.

[edDV]

Hi,

i have a 23min long video that has 1920x1080 resolution and is 1.5GB in size with a bitrate of 9730kpbs. I want to compress it on virtualdub using the x264 codec in order to keep the highest quality (HD) and make it as small as possible. What bitrate should i use to compress?

Thank you.

Are we to assume this is MPeg2 video? 9730 kpbs is already overcompressed for 1920x1080. What was the source? Broadcast? Also what type of show? Interlace, telecine or progressive?

For a typical progressive shot TV series (e.g. CSI), I cap the direct digital MPeg2 transport stream at about 15-17 Mbps (as broadcast), then use Handbrake in detelecine mode and contant quality around 18. Others may be satisfied with CQ at 20.

A CQ of 20 from a high quality source such as HD CBS TS, results in a bit rate in the 6-7 Mbps range. A 23 min show would generate a file ~ 1.2-1.3 GB in size.

[Hoser Rob]

There's also a lot more tthan bit rate if you want high quality and smaller files.

I saw an h.264 encode of Fellowship of the Ring yesterday someone else did. BR downsampled to 720p.

The guy used an adequate bit rate but didn't use high profile ... ie. no 8*8 DCT.

It stunk. I could make a better encode than that, in the same file size, from a DVD.

[RappinRod]

OK Im going to give you the best quality absolute lossless settings for a x264/ac3 stereo/MKV file that can be viewed in just about every media player out there.Only stupid apple products may not play this because they want you to use mp4/aac..I cheated on the audio to make the file smaller with NO video loss..1-Video-keep the same 1920X1080 resolution make the video bitrate 6190.You didnt supply a framerate so im gonna use 23.97 but use the same framerate thats in your video if you can..2-Audio,since you didnt supply the audio that is in the file,try ac3-192kbps-48000htz-2 channel stereo.Your filesize will end up being a little over a gig or 500 less mbs then your existing file..I dont know what type of video file extension you already have but im going to convert it and use the MKV/x264/ac3 output because it widely used and produces an excellent quality finished file.Now if you wanted a 720p file you wouldnt see much difference in video quality and the total file size would be 500 mb..I dont use virtualdub for file conversions,I use it for appending files only,,but their are other user friendly free encoders right here in video help like xmedia recode and their are others..Using the settings I gave you will produce a very high quality small file...Good luck...~

[yoda313]

try ac3-192kbps-48000htz-2 channel stereo

Just my personal preference but I almost never encode audio less than 384kpbs. Unless space is at a real premium audio (at least in the ac3 realm) doesn't usually take up a high percentage of the final file - dts and lossless hd audio is a whole 'nother story.

There is no reason not to use the original surround sound file UNLESS its for a player that doesn't like surround sound sources - ie a lot of portable players.

Other than that you should do alright with rappinrod's suggestion.

[budwzr]

This is getting confusing, but really it's simple.

Instead of bit rate, think in terms of quantizer depth, or spatial bits.

[supercain]

Thanks everybody for your advices. I finally decided to use 4000kbps and looks about fine. I cant notice the difference with the original so it was a good compression because now its 696MB. The original video was recorded from digital tv with the MPEG codec. Sound is at 192kbps and 48khz.