What's the best way to dump *all* information about a video file?

November 15, 2008 10:44 PM

What's the best way to dump *all* information about a video file?

I'm pulling my hair out trying to figure out the difference between some video files. One will stream over the web to my iphone -- the other will not. Another will start playing immediately in flash -- yet another one has to be downloaded completely before it starts to play. As far as I can tell from VLC and ffmpeg, these files are all identical, but clearly there's something different between them. How do I get all the encoding information for the files so I can compare them?

posted by crawl to computers & internet (7 comments total)

diff
posted by b1tr0t at 11:21 PM on November 15, 2008

gspot
posted by neckro23 at 11:48 PM on November 15, 2008

You don't mention the file type. But I wrote a file parser for a QuickTime and MPEG-4 streaming server a long time ago and I remember a few things.

If these are in fact .mp4 (MPEG-4) or .mov (QuickTime) files then the answer is that the two versions are laid out differently. The file format is flexible enough to support multiple ways of laying out the file.

If you are editing the video it is possible to lay things out so that you can edit in place, without having to rewrite the entire file just to change part of it. In this case the metadata (indices and so on) are generally all stored at the end of the file, since they are getting rewritten when you make edits.

For streaming it makes sense to put the metadata up front, or to interleave it with the data, or something like that, so that the client can start playing the file as soon as it receives the beginning. The tools you use to create QT/MP4 files will have an option to optimize the file for streaming, and you should use that if you aren't planning on editing the video any more.

If it's some other file format, I would guess that similar issues are at play, but I can't say for sure.

To answer your question a bit more directly, there is a program called "Dumpster" that you can download from Apple here that should work for .mov and .mp4 and will let you dump the stuff inside the file.
posted by sergent at 12:59 AM on November 16, 2008

Video Inspector may help.
posted by fire&wings at 2:49 AM on November 16, 2008

You could give MediaInfo a try (Windows and Linux).
posted by monkeyforest at 5:06 AM on November 16, 2008

I spent hours trying to work this out. The reason to my problem was that Final Cut Express put the index at the end of the file when encoding to MP4 (you have the option with MOVs but not MP4s) which meant that the file needed to be fully downloaded before it could start playing it.

The answer was here. You'll need to download Adobe AIR to run the linked program, but if your cause is the same as mine (and the symptoms sound the same) then it'll work.

Good luck, and I hope it helps!
posted by Magnakai at 9:07 AM on November 16, 2008

Thanks for all the suggestions!

Magnakai, that certainly fixes my MP4 streaming to Flash issue. Now to get it integrated into my workflow somehow.

monkeyforest, MediaInfo gives me lots of info on my iPhone MP4s. The only difference appears to be that the one that doesn't work is Baseline 2.1 and the one that does is Baseline 3.0. Apple's site says that Baseline 2.1 should work (and indeed, the video plays on the iPhone, it just won't work embedded in a web page.

Video Inspector doesn't open MP4s. Dumpster gives me lots of stuff I don't understand ;-)
posted by crawl at 10:44 AM on November 16, 2008