Best Video Compression Methods

[mindtreaser1]

Hello all,

I am somewhat new to video compression so I need some help.

I have about 220 avi & Mp4 files that differ in size from 1.2GB to 2.5GB that I want to compress.

FILE INFO

Video info:
Codec: H264 - MPEG-4 AVC (PART10)
Resolution: 1280x720

Audio info:
Codec: A52 Audio (aka AC3) (a52)
Channels:Stereo

I am unsure of what software to use and what settings would be best, advice please?

[fcorbelli]

i do not think that you can gain much because 264 is already very efficient. you can try x265 and use vlc to play

[mindtreaser1]

I was worried that might be the case. Could I convert to MKV and try downsizing the files that way?

[fcorbelli]

I was worried that might be the case. Could I convert to MKV and try downsizing the files that way?

I do no think so, because mkv is almost only a container, so your MP4 files will be... MP4 embedded on MKV.
You can get real shrink reducing resolution and/or quality

[mindtreaser1]

i do not think that you can gain much because 264 is already very efficient. you can try x265 and use vlc to play

What process do I use to make into x265?
Although from my experience with x264 vs x265, 265 is a slight loss of quality with very little difference in size reduction, would you say this would be the case?
And what kind of reduction in size would I get from the change to 265, from say, a 2GB video?

[fcorbelli]

very small. try yourself. but i suspect there is not space for significative gain.

[mindtreaser1]

So there really isn't anything I can do to reduce the space these files are taking up then huh?
I just realized I could possible just zip/rar them, although that is impractical.
Does this sound like a good idea to you? If so, should I zip them individually or with many?

[fcorbelli]

i do not think you can get. more than say 1 to 5% with for example 7zip.but then you cannot see without unpack.

[mindtreaser1]

That's what I meant by impractical, but they aren't necessarily files that I look at often.

Thanks for all your suggestions though, I'll try a few things and then reply with the results.

[SvenBent]

So there really isn't anything I can do to reduce the space these files are taking up then huh?
I just realized I could possible just zip/rar them, although that is impractical.
Does this sound like a good idea to you? If so, should I zip them individually or with many?

You can easily make the files smaller with lossy encoding it a question of quality if you are ready to toss away quality you can just re encode them at a lower bitrate. but you haven't really giving any information in your question besides getting them smaller. And yes that is easily possible

in regards to 7-zip it only make sense to compress them together if you go in a solid mode with a dictionary big enough to cover more than one filem=, even thoug it might not even help. also in this way you have to decompress the entire archive before playing and not just the file you want to play.


only sane option would be to check what last layer lossles compression the you h.264 stream is using. if its not cabac. find a tool to decode this layer and reencode with cabac. however most encoders use cabac as default in my experience


if you really want to put thme into a new compression layer/container like 7-zip maybe look into srep instead.


-- edit --

i just saw you have yuo audio in ac3 file format. you might wanna consider reencode it to aac instead. use yam do etrac the ac3 stream. use azid to make it into a .wav/pcm file. use Qaac to encode it to aac.
use yamb extract the h.264 stream . use yam to mux the h.264 & .aac stream together into one .mp4 file.

AFAIK ac3 is a pretty inferior audio format ( worse then layer3 in general )
but reencoding will always introduce a slight drop of quality

[fcorbelli]

ahem... but using hundreds of cpu time to gain few bytes is not a very big gain, at least for me.
as previously stated reducing resolution can quadratically reduce frame size (not of course compressed one), but with sensible loss of quality.
so... buy a bigger disk should be the most effective solution

[ggf31416]

As SvenBent said your best bet is converting the ac3 into aac. Since h265 encoders are not madure yet the bitrate savings are not large compared to h264 encoders like x264 (often considered state of the art for h264).
With regards to the video stream if there are significant variations in quality (or bitrate if estimating the quality is too time consuming or the complexity of the content is similar) among the videos you can reencode the high quality videos to a lower bitrate. I would advice not reencoding videos with low quality or bitrate since the loss from reencoding depends mainly on the target bitrate, not much on the source bitrate (and in some cases, if the encoder is optimized for uncompressed sources, going from low to low may actually result in more loss), so usually is not worth reencoding low bitrate videos.
As fcorbelli said another option would be investing USD 100 on a external hard drive, even in countries with high customs taxes like mine they are not very expensive.