Attempting to Compress MP4 Files
 

As per the title, I'm trying to compress MP4 files, but I'm having difficulty in getting any compression of the files so far.

From searches here, it appears that SREP should be used first followed by LZMA for final compression. SREP settings as per posts at this forum could be -a2 -m5f -l512. Unknown what setting(s) used for the LZMA compression.

How to achieve best possible compression of MP4 files please?

Using SREP, LZMA, and/or other precompressors/compressors?

And what settings should be used (in general) for compressing MP4 files?

Process MP4 files via Freearc? 7zip? or what?

Thank you.

Sample MP4 video enclosed for testing.

Test Video

^^
Videos don't compress well, so just use srep. Anything more is wasting time.

The only video type that compresses only kind of well is bink videos (bik, bk2) because there is a specialised tool for it (bink_pack).

Other video formats, mp4, webm, avi etc etc etc all just use srep.

Uhm, MP4 videos are already compressed, at least the video stream.

Thank you for the comments.

Until a specific compression tool for MP4 comes along, I'll have to use SREP.

Any particular or best options to set for SREP like -m3f or -m5f etc etc? Or do the options depend on the actual encoder used for the MP4 container?

^^
There will never be a specific tool for mp4, as kaktor said the video is already compressed.

OK.

Suggested SREP settings?

^^
-m3f is fine.

Try it find FAILSAFE methods? (ignored many srep errors during decompression.)

Trying use internal LZP compression faster than lzma and betterly compress, incompressibble data or use very strong compressors. Likely LOLZ or RAZOR. This two compressors very goodly compress hardly compressibble data than others. (avg. 0.5-1% to upto 2-3% or better.) Default srep settings = bigger results this sample file. Try l32-64 settings need more memory from biggest datasets and not guaranteed failsafe decompress, except minimally better ratio. MSC/BPK/OGGRE not enhance ratio/compress the data.

Few quick test results added in TXT-file. (zipped)

Thanks for the detailed tests!

Yes, it seems at this time from doing some testing myself now, that Razor compressor seems to give the best compression result so far!

FreeARC Command Line Usage
 

Partly in relation to compressing MP4 files, I'm experimenting with the command line version of FreeARC (Arc.exe) and using additional (pre)compressors in association with Arc.

For example I've tried this manually entered command -

but get error message -

"Arc: user error (Unsupported compression method or error in parameters: srep)"

Srep executable (srep.exe) is located next to arc.exe within the same directory.

And arc.ini (located within same directory as arc.exe and srep.exe) has an entry for srep as follows -

So what is wrong with the command to run srep via freearc?

Try it: -msrep or -msrep+lolz/razor or -msrep:m3f:l512(or smaller l# values):a0
This CMD window navigated to FreeArc\bin directory? Or use FreeArc GUI? Win7 x64 differentially resolve cmd/path related commands than XP.*

See the 'mp4.txt' file used commands...

*Very strong example:

WinXP: move data.bin data.7z --> equal to "ren" console commands.
Win7: move data.bin data.7z --> worser scenario, destroying the whole file! Better scenario, workly rename.

Thanks for the comments.

I'm suspecting the issue of arc not working properly may be because I have several other programs that also have the arc.exe included. So when I attempt to run the arc command, the command may be selecting another location of arc.exe and not the arc.exe within the Freearc directory.

Presently trying to remove paths to the other programs containing arc.exe and see how things go. And trying to run arc.exe from the current working directory of Freearc\bin.

EDIT: I managed to get Arc.exe working with methods by copying Arc.exe and Arc.ini and srep to the current working directory which contained the test mp4 file.

The initial problem of Arc not working properly was most likely due to the presence of multiple copies of Arc.exe and Arc.ini within several other programs which were causing conflicts with each other.

EDIT2: Did some compression tests on 70 MP4 files ranging in size from 547 kB to 11,351 kB.

NOTE: for compression options using lm4 for files, files fail to decompress! Do not use lm4 option!

There is not a great difference in final compressed file sizes regardless of compression method.

Not really the best ideal final compressed sizes, but MP4 files are difficult to compress.

brispuss: LOLZ is the right choice. (especially if x86 compatibility is also a consideration, when unpacking.)

Can someone share the very first LOLZ version? (2016.12. release.) Is this version "compressor" 32 or 64 bit? (cls-lolz.dll found only x86 version.)

brispuss: Don't use different configuration than lm0 compression settings! Other lm1-2-3-4 its used (not totally removed) any special/older methods from LOLZ code, its works only from compression, will create not decompresseable archives. Try it testing lm4 compressed archives, still crashing now! (Yes, this ratios better than lm0 mode only...)

Yes, thanks for this caution!

I was about to make a post as to why files compressed using the lm4 option failed to decompress!

It is now my understanding that the option lm is not fully/properly setup/coded, so that is why files fail to decompress with lm compression options lm1 ~ lm4. lm0 option seems to be fine though.

File Types and/or (Pre)Compressors
 

I was reading a text document about a week ago that describes in some detail the file types, and/or the (pre)compressors used in compression. I didn't finish reading this document which I thought I had on my computer, but I can't seem to find the document now!? I think I originally downloaded this document from this forum, but on searching this forum, I can't seem to find this document (again)?

The document author was I think someone fairly well known on this forum (Razor?, Masquerade?, Panker?, Blackfire?, or ??), but I'm not sure.

Can anyone please locate this document?

Thank you.