UnpackMP4 - an MPEG4Modifier / UnpackCL clone

[barakori]

Hi, I converted UnpackCL (the command line version of MPEG4Modifier) to Java, so that it can be used anywhere Java is available. Under Windows, this version is almost twice as fast as UnpackCL, and under Linux, it's very easy to convert multiple files in a single invocation. I want to thank moitah for the original UnpackCL. I know nothing about VOPs, VOLs and other MPEG4 and AVI internals. I just converted the code to Java.

Please try it and tell me what you think. Download it and find more information at http://www.xmixdrix.com/tools/unpackmp4.html.

[bond]

nice, but your tools name is slightly misleading as "mp4" most of the time refers to the .mp4 container, which your tool doesnt support

[Moitah]

Wow :D! I will take a look.

[Moitah]

I didn't actually try it yet, but your performance results are interesting. I should try different file I/O methods to see if I can improve speed as well. The BitStream change looks good too.

I noticed it was based on an older version (1.3.2 I believe), you should update it to 1.3.4 when you get a chance because it includes an important bug fix. I think the only file I changed in 1.3.3/1.3.4 was MPEG4FrameModifier.cs, so you can just use a diff utility on that file.

Nice work!

[barakori]

Regarding the name - I'm opened for suggestions. Please help. I thought UnpackAVI is also misleading, since AVI can contain other formats inside, and UnpackCL is already taken ;-)

Regarding the BitStream - I checked and it turns out that in all copy operations, the bit position of the read is the same as the bit position of the write, so I optimized the bit splitting to be done only once. That's the main improvement there. I assume it's like that because the bit operations correspond to some kind of structure that's true for both input and output file (again, unlike Moitha, I don't know anything about the structure of the file.

I'll check the latest version and try to implement...

[bond]

if it only does unpacking packed bitstream call it UnpackPackedBitstream ;)

[barakori]

Okay, I modified UnpackMP4 AVI (This would be the official name to denote it's working on AVI files) to match UnpackCL version 1.1.2 (MPEG4Modifier 1.3.4). I actually saw an AVI that was converted with a problem (inconsistent B-Frame if I remember right), and after the change the conversion was flawless :-). Again, thanks to Moitah.