Jpeg EOF

I'm trying to find out where the JPEG file ends, mainly to find out whether there's any information appended to the end of the file. I've tried searching for the EOF (FF D9), but to my surprise, this is repeated multiple times in the file in 1 out of 5 files.

Is there a way to safely determine where the JPEG file ends?

http://www.ijg.org/

Not without actually parsing it.

That just sounds too retarded. Identifying the EOF is no problem at all in any other major format. Are there any good parsers for, say, C#?

JPEG isn't retarded, you are.

>>4
If you're using .Net, then at least use F# for your parser.

>>5
Derp.

>>6
I'll have a look at F#, thanks for the suggestion.

>>7
YHBT.

>Not without actually parsing it.

That is fucking gay.

>>1 "I've tried searching for the EOF (FF D9)"
What are you, retarded? A filesystem might use that byte sequence to mark the end of the file, but it doesn't pass it along to a program that reads the file.


char mychar;
ifstream idort;
idort.open("dicks.jpg");
while( idort.get(mychar) )
   DoShit(mychar);

to find out whether there's any information appended to the end of the file.
Hey dumbass, how about you just check whether the file ends in ffd9?

>>12
What if the appended data ends in $ffd9?

>>13
i guess the file would be corrupt

>>14
You guess poorly.

>>13
Then you've probably appended a JPEG to a JPEG. Which would probably be a stupid thing to do. And if >>1 wanted the check to be robust, tha'd just parse the file.

>>16
what about

cat file.jpg longstory.txt - < `echo -n "\0xff\0xd9"` > anotherfile.jpg

>>17
probably

file file.jpg

Nevermind, I'll just find the last FFD9 in the file and look for popular filebinder-headers while I do so.

Nevermind, I'll just hax my own anus.

Just fucking use a jpeg lib.

JPEG 2000 is fucking amazing compared to JPEG.

>>22
Pragmatic programmers? In MY /prog/?

>>24
It's more likely than you think.

http://www.ihateyoujulia.com/?id=1f5463f4415b70afbb3ba55a69db1726

>>26 DON'T CLICK IT!!!!

>>27
I clicked it just to spite you.

>>28
How was it?

>>29
Disappointing.

>>28
You're only spiting yourself.

>>31
How am I licking myself?

>>32
I would assume with your tongue.

>>1
You should parse the FF,D8 and FF,D9 pairs as you would parentheses. JPEG streams sometimes contain other JPEG streams inside them for thumbnails.

>>34
Damn, I knew there were some simple solution to it. Thanks!

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So there can't be sequences FF,D8 FF,D9 anywhere in JPEG streams? Why did they do it? Simplicity of parsers?

>>37
There can be those sequences inside the JPEG stream besides the tags.

Look, it's not that difficult, you shitbag wannabes.  JPEG is a compression format.  They're not going to put any extra bytes in that can be inferred from elsewhere, nor are they going to bother with adding escape codes around FF D8|D9 pairs just so your lazy ass can grep for them.

>>38
nor are they going to bother with adding escape codes around FF D8|D9 pairs just so your lazy ass can grep for them.
Actually, remember that the JPEG bitstream format was designed by idiots. It is not sensible like PNG. From the JPEG standard:
byte stuffing: A procedure in which either the Huffman coder or the arithmetic coder inserts a zero byte into the entropy-coded segment following the generation of an encoded hexadecimal X’FF’ byte.
In order to ensure that a marker does not occur within an entropy-coded segment, any X’FF’ byte generated by either a Huffman or arithmetic encoder, or an X’FF’ byte that was generated by the padding of 1-bits described in NOTE 1 above, is followedby a “stuffed” zero byte (see D.1.6 and F.1.2.3).

>>39
0/10
learn your fucking algorithms, newbie