compressing video filesize for storage

[azor]

Hi, my HDDs are full, and most space is taken by videos.
I don't want to delete anything, instead I want to compress the video files to H264.
Most of the source files are in WMV,XVID,DIVX. but I have files of any codec, resolution, framerate and bitrate.

What I'm looking for are the best settings to achieve a good compression and get small video files while maintaining a decent quality.

Since all video files have different codecs/resolution/framerate and content I can't use a fixed bitrate.
Instead I need a fixed value to convert all that files with same quality:filesize ratio.
I came up with 2 possibilities: either calculating "Bits/(Pixel*Frame) rate" and use the same value for all videos, or quality based encoding. Are there any other options ?

Can you please give me recommendations on what to use? All tips are welcome (a specific h264 encoder, specific encoder settings, presets, etc.).

Thanks in advance!

[Baldrick]

Buy a new HDD. It's not worth reconvert already heavily compressed video.

[hech54]

Buy a new HDD. It's not worth reconvert already heavily compressed video.

What he said....^

[yoda313]

Here's another vote for a new harddrive.

If they were of a higher source to begin with I would recommend converting. However this is not a good idea to compress an already compressed source.

If you want a short term easy solution burn them to dvds with imgburn and delete them off your drive. Then you can get back to the videos once you get some more harddrive space.

[zoobie]

buy a new harddrive...I saw a 2TB internal for $79 somewhere recently

[azor]

Oh... I shouldn't have mentioned that my HDD is full as a thread opener, should have foreseen that it would turn out into a "buy new HDD"-thread.

I got 2 TB and they're full ok. >90% of the videos waste too much space. There are three reasons for this:
1. people are stupid and use 1-click tools to convert videos, and then you have like 640x480@25fps with a 4000 kbit/s or 1280x720@25fps on up to 6000-12000 kbit/s.
2. they want to provide videos in perfect quality
3. obviously WMV, XVID/DIVX, MPEG2 and others are by far not as efficient as H264 can be. People have proven that you can get a decent video qualitiy for 1280x720@24fps with only 500 kbit/s if you use H264.

I want to convert most of my stuff (the biggest files), and any videos that I will download in the future. And I don't need perfect, top-notch quality.
That's what it's all about. I would have to buy more and more HDD's, but I could save at least 60-70%, maybe more % of the disk space If I convert them efficiently.

So please back to topic, thank you.

[PuzZLeR]

For similar reasons, I too, and will still, say buy a new hard drive as the best solution. Also, regardless of what formats your files are in, they are still your Source - and you should always have a copy of your Source even if you decide to convert, since compressed conversions lose quality. If you had large lossless files, or DV, then I'd understand, but it's not a feasible solution with already highly compressed formats. And H.264 is efficient, but it's not magic - you will still lose a ton of quality anyway.

The reason you should be converting and compressing is for playback options, not really to change your Source.

Since all video files have different codecs/resolution/framerate and content I can't use a fixed bitrate.
Instead I need a fixed value to convert all that files with same quality:filesize ratio.
I came up with 2 possibilities: either calculating "Bits/(Pixel*Frame) rate" and use the same value for all videos, or quality based encoding. Are there any other options ?

Ok, if you still want to convert, let me give you some advice.

Unless you want an exact size a "fixed bitrate" is wrong thinking for uniform quality. Even if all your video files were of the same codec and dimensions, it still wouldn't work - all video is different in terms of motion, complexity, colors, etc. and all will require different bitrates to achieve the desired quality result. A fixed bitrate will either add too little or too much bitrate to a great majority of your content.

The good news is that you don't have to figure it out - use constant quality. Only one pass and you will end up with the appropriate bitrate for the quality you seek.

[azor]

For similar reasons, I too, and will still, say buy a new hard drive as the best solution. Also, regardless of what formats your files are in, they are still your Source - and you should always have a copy of your Source even if you decide to convert, since compressed conversions lose quality. If you had large lossless files, or DV, then I'd understand, but it's not a feasible solution with already highly compressed formats. And H.264 is efficient, but it's not magic - you will still lose a ton of quality anyway.

The reason you should be converting and compressing is for playback options, not really to change your Source.

They're just videos that I don't care about toooooo much, especially regarding top-notch quality, however I still want to keep them.

Unless you want an exact size a "fixed bitrate" is wrong thinking for uniform quality. Even if all your video files were of the same codec and dimensions, it still wouldn't work - all video is different in terms of motion, complexity, colors, etc. and all will require different bitrates to achieve the desired quality result. A fixed bitrate will either add too little or too much bitrate to a great majority of your content.

That's what I said in my post.

I know "Bits/(Pixel*Frame) rate" doesn't consider motion, complexity, colors, but at least bits/pixel/framerate, and VBR could help a bit.
But yeah that's what this thread actually was supposed to be all about. You say I should use constant quality.

What's the most efficient constant Quality value in terms of quality:filesize? Do you know any sites who tested this? Is 2-pass any good for this, I usually prefer 2-pass but I usually use bitrate based vbr or cbr.

[qpskfec]

3. obviously WMV, XVID/DIVX, MPEG2 and others are by far not as efficient as H264 can be. People have proven that you can get a decent video qualitiy for 1280x720@24fps with only 500 kbit/s if you use H264.

720p @ 500k = crap, these people have proven they have a low threshold for "quality"

[hech54]

If you don't care too much about quality....just load them into WinFF and batch encode them. The only problem (again) is....where are you going to put these newly converted videos if your 2TB HDD is already full?

[azor]

3. obviously WMV, XVID/DIVX, MPEG2 and others are by far not as efficient as H264 can be. People have proven that you can get a decent video qualitiy for 1280x720@24fps with only 500 kbit/s if you use H264.

720p @ 500k = crap, these people have proven they have a low threshold for "quality"

Well, then you probably didn't hear about Fabio Sonnati h264 experiments yet.

http://www.flashvideofactory.com/test/DEMO720_Heima_H264_500K.html
http://www.progettosinergia.com/flashvideo/comparison.htm
http://3172.voxcdn.com/DEMO720-Heroes500.html

they look pretty good on my screen

If you don't care too much about quality....just load them into WinFF and batch encode them. The only problem (again) is....where are you going to put these newly converted videos if your 2TB HDD is already full?

well, it's not that full my internal HDD currently has 100GB of free space, but it wouldn't take that long.. :P

[Baldrick]

Lots of blocks and blured image in fabios h264 examples. Heroes looks like crap. But you still need a good source to get similar results.

[azor]

Lots of blocks and blured image in fabios h264 examples. And you need a good source to get similar results.

it doesn't look HDish all the time but for just 500kbit/s I think it's damn good. Just compare this to a youtube or random video sites 500kbit/s.
If it wasn't in 720p it would probably look much better.

So if I'd use a higher bitrate and good settings it would be fine.

I'm also thinking about lowering the screen size, because I don't need 720p for all videos. And also 24-25 fps instead of 30-60fps would be ok.
Would changing the framerate from lets say 30 to 25fps be any bad?

[qpskfec]

Agree with Bladrick. The Heroes scene on my PC monitor looked like crap. It would look even worse on a large screen TV.

Note that the clip is a scene with very little motion and still showed a ton on macroblocking. They picked a low motion scene on purpose to avoid worse artifacts.

Comparing to Youtube and other random sites is comparing crap to garbage.

[PuzZLeR]

They're just videos that I don't care about toooooo much, especially regarding top-notch quality, however I still want to keep them.

Well, if you don't care that much, and you accept you will lose quality and invest some time, then converting to H.264 as a replacement is indeed a better option to save on space.

I know "Bits/(Pixel*Frame) rate" doesn't consider motion, complexity, colors, but at least bits/pixel/framerate, and VBR could help a bit.

Yes it will "a bit". It will only help ceteris paribus - all things being equal - that is, if every video had equal complexity then the other quantitative metrics apply. For example, if you're encoding half the amount of pixels at half the frame rate then you could factor that in.

Again, this isn't realistic since all video is different and even so, why bother? Constant quality will adjust this for you anyway - it will take account of different sizes and framerates, details, etc too in the final conversion.

You say I should use constant quality.

What's the most efficient constant Quality value in terms of quality:filesize? Do you know any sites who tested this? Is 2-pass any good for this, I usually prefer 2-pass but I usually use bitrate based vbr or cbr.

A long, long debate with x264, for several years, has pretty much ended with near unanimous agreement that any quality difference is frivolous between a 2-pass VBR encode against a CRF encode at the same bitrate. (CBR is horrible - avoid).

So in other words, one pass with CRF (Constant Quality) will be just as efficient at the same settings and bitrate as doing it with 2-pass VBR.

Having said that, the beautiful thing about using CRF is that you don't know the final bitrate until it's done. In other words, it figures it out for you, in one pass, by adding extra bitrate in complex scenes, lowering bitrate for others (such as black screens, stills, etc) - automatically. You will overcook, or undercook, using a prescribed self-determined bitrate for 2-pass VBR for quality measurement.

As for an "efficient" constant quality value, with most sources, IMO realistically, any value between crf=18 to crf=21 is acceptable. The lower the number, the higher the quality and the higher the file size - so it's up to you to experiment.

I believe anything under crf=17 produces too big a file and anything over crf=22 produces varying levels of "mud".

Keep in mind when using constant quality that the mindset isn't the same as VBR 2-pass.

With VBR 2-pass you think: "What is the highest bitrate I will accept?" (To obviously get the highest possible quality.)

With CRF you think: "What is the lowest quality (highest CRF value) I will accept?" (To obviously get the lowest possible bitrate.)

[yoda313]

I'd still say burn the original downloaded videos to dvd just to be sure. Than if you change your mind about something you can always go back to the "original" quality level.

Even if you don't care about the quality on them something can always go wrong or new techniques come up and you'd want to start over.

[PuzZLeR]

I'd still say burn the original downloaded videos to dvd just to be sure. Than if you change your mind about something you can always go back to the "original" quality level.

Even if you don't care about the quality on them something can always go wrong or new techniques come up and you'd want to start over.

@Azor: This is pretty much why keeping a copy of the Source is crucial. Things change, mistakes happen, better filters come out, DvD, blu-ray, better codecs, etc - so keeping a copy of the Source always gives you the best reset quality option possible instead of degrading it over a series of encoding generations among lossy formats.

Having said that, keep in mind - yes, H.264 is indeed most efficient. But don't expect it to produce something better quality than your DivX or WMV source. It will be worse regardless of the bitrate. H.264 would have only produced better quality at lower file sizes if, hypothetically speaking, you encoded directly from the source that produced the DivX and WMV files.

Even if your Source is some cruddy and blocky old 240p MPEG-1 file - it's still your Source and encoding it to H.264 isn't going to make it better. (Maybe smaller, but not better.)

[mauldin.doris]

I am trying to compress video files because it is so large when submitting to my online classroom. I have tried using prism file converter but it only converts files, I need to compress files. How do I do this?


Doris

[guns1inger]

Filesize = running time X bitrate. Anything that converts can compress, just set the bitrate to an appropriate level and choose a suitable codec.