Looking for a way to enable someone to upload a single file which will be series of image files (all gif) merged together as one big file. Here is what I need to do:
Using VB6, want to merge the image files (potentially dozens of them) into a single file
Upload file to a PHP Script (easy enough)
Have PHP break apart the single file and write image files
I know how to handle the uploading of the file. I also know how to write the image files in PHP. What I am unsure of is the merging/un-merging operation.
In theory, I should just be able to use VB6 to merge all images using binary read/writing. However, does anyone know the series of binary codes that prefix each .gif file so PHP can pick up on that, or do I need to write some sort of binary separator in between each merged image?
I could surely tinker with this myself, but I thought some of you smarter-than-me coders may have already done this, and/or could provide a link, some code, or some 'things to consider'.
Thanks.
Instead of merging/un-merging, if the whole purpose is to avoid overhead of sending dozens of files, why not zipping them and unzipping in PHP?
That should be far easier than the merging operation you're proposing.
Here's a free Zip/Unzip library for Windows: Info-ZIP
Here's some sample code that uses Info-ZIP: Zip and Unzip Using VB5 or VB6
Here's PHP's documentation on the ZIP module: php.net/zip
Here's an example of how to use "unzip" command through PHP, rather than using the Zip module: Zipping and Unzipping Files with PHP
Google is your friend :)
Related
hi i wanted to know if uploading large files like videos ( over 200 mb - 1gb) from php is a good option after setting up the server configuration like max_post_size , execution time etc. The reason i ask this question is because i read some where that when a large file is uploaded , best practice is to break that file into chunks and upload it ( I think youtube does that). Do i need to use another language like python or C++ for uploading large files or is php enough. If i need to use another language can anyone please help me with reading material for that .
Thank you.
PHP will hold the entire file in memory while the upload is happening. That means that if you are uploading 5 files in parallel, then at the very most you will need 5GB+ of memory.
This can be done in PHP, and I have done this using a chunking method. There are several SO questions on this topic:
File uploads; How to utilize “chunking”?
Upload 1GB files using chunking in PHP
But my personal preference is to use plupload. It is a very complete cross-platform (JS, Flash, Silverlight) upload script with a nice PHP code sample to handle chunking.
Its not only PHP to be considered for large file uploads. Your web server also need to support that, at least in nginx. I don't know how httpd handles that, but as you said splitting in chunks are viable solution. FTP is another option.
I allow PDF files to be uploaded to my site (PHP).
I would like to offer the ability to also allow .zip files which contain PDF files in directories so it is easier for users to simply zip a directory and upload one file instead of uploading multiple zip files individual.
For those of you who offer a .zip file upload feature to your (PHP) website, what are the technical, security, and other issues you have faced?
Be careful how you unpack the zip, you could find yourself consuming far more resources than you expected. Perhaps some setrlimit(2) resource limits before unpacking would be wise.
The unzip(1) utility has several nice safety features built in; the -^ command line option turns off control-character filtering, so make sure you don't touch this :) and the -: command line option allows stupid pathnames like ../../../../etc/passwd. Make sure you're on at least version 5.50, so that those stupid pathnames are forbidden by default. (And don't use that command line option. I mention the options just so you can more easily find the documentation for them. :)
If you use an API, make sure it has options to prevent both kinds of silly filenames.
Assuming the .zip gets unpacked eventually you would have to make sure the directory they get unpacked in is unreachable by the the clients' browsers (with .htaccess or by placing it outside the web root directory), and even in that case I'd still monitor the contents of the unpacked .zip to make sure they didn't contain anything that might prove harmful (php or other files run by the server, html spoofs).
Another issue is i guess the upload_max_filesize set in php.ini, you can make sure it can be set big enough to suit your purposes before you start coding.
edit: also read sarnold's answer ;)
AFAIK, php can handle zip files pretty efficiently. Difficulties/Issues that I can think of is, while accessing the file where We need to extract the zip first, and then retrieve the actual needed file. Due to that reason, extracting a zip, might consume additional amount of server time, depending on the size of the file itself.
Where As, during uploads, I do not suppose there is any difficulties or issues specially emphasized on zip types.
Does anyone know if there is a "best practice" to concatenate mp3 files to create new files, while preserving the original files?
I am working on a CentOS Linux machine, in command line. I will eventually call the command line from a PHP script.
I have been doing research and I have come up with a process that I think could work. It combines general advice from different forums, blogs, and sources like this one.
So here I go:
Create a temporary folder
Loop through files to create a new, converted copy, of file into a "raw" format (which one, I don't know. I didn't know "raw" files existed before too long ago. I could use some suggestions on this)
Store the path to the temporary files, in the temporary folder, and then loop through the files to concatenate them and then put the new merged file the final "processed directory"
Delete the contents of the temporary file with the temporary raw files inside.
Convert the final file from "raw" to mp3 and enjoy the finished result
I'm thinking that this course of action might be best because I can't necessarily control the quality of the original "source" mp3s.
The only other option I could think of would be to create a script that would perform a similar process upon files being added to the system leaving only the files with the "proper" format and removing the original "erroneous" file.
Hopefully you can see that I have put some thought into this and that I'm trying to leverage the collective knowledge of this community to choose the best direction.
Perhaps there is a better path that I could take?
By concatenate, I mean to join together in sequence to create a new audio file from the "concatenated files."
I currently have the following installed:
- Sox
- FFMpeg
I'm currently using the sox like this:
sox file1.mp3 file2.mp3 newfile.mp3
By using 'cat' command? This will mangle the mp3 file format by "creating an array" (as it were) of mp3 files within a single mp3 file, with the resultant mp3 working only if the player software is smart enough. So, if you can find and install mp3wrap you could:
mp3wrap output.mp3 `ls -1 *.mp3 | sort`
I wrote a PHP script to dynamically pack files selected by the client into zip file and force a download. It works well except that when the number of files is huge (like over 50000), it takes a very long time for the download dialog box to appear on the client side.
I thought about improving this using cache (these files are not changed very often), but because the selection of the files are totally decided by the user, and there are tens of thousands of combinations on the selection, it is very hard to cache combinations. I also thought about generating zip archives for individual files first, and then combining the zip files on-the-fly. But I did't find a way to concatenate zip files in PHP. Another way I can think of is sending (i.e., reading) the zip file at the same time as generating it. I also don't know if this is supported.
If someone could help me on this, I would really appreciate your help.
To extened Mike Sherov's answer, try using a combination of Tar and Gzip/Zip. Individually pre-compress all the files using Gzip/Zip, Then when the client makes their selection, you simply Tar those files together. That way you still get the benefit of compression and the simplicity of downloading one file, but none of the overheads and delays associated with compressing large files in real time.
While not a silver bullet, you can try tar'ing the files instead. The resulting file is larger, but compression time is much shorter. See here for more info: http://birdhouse.org/blog/2010/03/08/zip-vs-tar-gzip/
Check out mod_zip for Nginx:
https://github.com/evanmiller/mod_zip
It streams a ZIP file to the client dynamically and can include very large (2GB+) files while using very little RAM.
I was wondering if is there a way for php to check if a PDF file stored locally on the server is corrupted or not. We have a php application that deals with a lot of scanned documents converted in PDF and it would be nice to check which of them is corrupted to alert the user.
I tried to look around but with no luck.
There are versions of pdflib available which can read PDFs - you could simply try to open and read each page with that.
The problem is there are many ways a PDF file can be corrupt.
Maybe your best solution would be to find a PDF reading lib and try to extract the first word from each page or something. That would at least catch some basic types of corruption.