This is a bit of a weird question but, with the functionalities of C++, c# and objective C as we speak is there any possible way for video content to be uploaded whilst its recording. So as you record the video it would be being compressed and uploaded to a website.
Would this involve cutting the video into small parts as you record, hardly noticeable stops and starts during the recording?
If anyone knows if this is at all possible, please let me know.
Sorry for the odd question.
You've just asked for streaming media -- something that's been done for over a decade (and, if you overlook "television", something that's probably been underway in research settings for several decades).
Typically, the video recorder will feed the raw data through filters of some sort -- correct white balance, sharpen or soften the video, image stabilize, and then compress the raw data using a codec. Most codec designs will happily take a block of input, work on it, and then produce a block of encoded data ready for writing. Instead of writing to disk, you could "write" to a socket opened to a remote machine.
Or, if you're working with an API that only writes to disk, you could easily re-read the data off disk as it is being written and send the data to a remote site. You'd have to "follow" the writing using something like tail -f's magic ability to follow the file as it is written. (Heck, if you're just bodging something together for a one-off, I'd even recommend using tail -f as part of your system.)
It depends on if the application recording to disk is locking the file. My guess is that, unless you wrote the recording software, the application locks the file(or doesn't even create the real file) until it stops recording. If you are writing the recording software as well, then yes, you can do this. you would just use sychronized threads.
Related
I developed a socket based p2p system where i stream mp4 video from a client to a server. The video data are transferred using byte[].
The transfer works, however i am struggling to figure out how i could play, in continuous, a mp4 file being transferred to another PC? The PC application, that would play the file, is in WPF.
I tried using a MediaElement to play the file, being written to the disk, but for some reason it doesnt play at all. I can play it with VideoLan tho.
Any hint of where to look? I am lost from here!
Thanks in advance!
Its going to be different with every player. Mp4 is probably the worst possible container for this application. The container is designed to be used with random access media, such has a hard disk. The player has the ability, and sometimes requirement to seek around within the file, and not just plat start to finish. Either you need to make the protocol mp4 aware (parse the file, and download the block that will most like be needed next), or use a streamable container such as TS, or flv.
Its is also possible that the player knows the file is incomplete. The atoms sizes are encoded within the file. If the file size doest match, the combined atom sizes, the player could assume a corrupt file.If this is what is happening, you can try to pre allocate the file. it may trick the player enough to play
I´m doing a "Whatsapp" like app and I need to send user videos (from camera/gallery).
I need to send video from ios to android and from android to ios (windows phone in the future).
First thing I thought is to use camera params to record the video in low resolution, but that won´t help with recorded videos stored in the phone already.
Second thought was to zip the video file, but I guess this is not enough for very large files.
Third: actually compressing the video file generating a new file, and then zip it before sending it through the network.
So this is what I need before actually sending the video:
Compress the video file, generating a new file that will play nicely in
both platforms (ios and android)
Make the compressing process aysnc(as I don´t want to block the UI
thread for a really long time)
Zip it (this is the easy part, just for the record)
Any ideas or help are appreciated
You would best need to use your platforms framework to also leverage existing hardware support for encoding (mainly h.264 hardware encoding). A PCL solution would eat to much battery as it would need to run on CPU only giving you bad performance and even worst battery live.
This ties in with 1. Just use your platforms native method to execute the frameworks methods async.
Skip this part. It will increase overhead and disallow video streaming There are virtually 0 benefits from using a zip algorithm on top of an already compressed video stream.
Just make sure that you end up with a cross platform compatible video format like H264.
Given the path of a string i want to wipe out the contents of a file. The natural way I thought (which maybe incorrect) was to open a FileStream to the file and write gibberish (random data perhaps taken from a RNGCryptoServiceProvider) to it. And then perhaps do this several times and then delete the file.
My problem is that while this may look logically correct, i read up on another blog that Windows might actually choose to write the file to a different place in the hard disk.
Is that the case in Windows Mobile? Will this actually be a problem? Does this writing to a different location in the hard disk apply to even flash based (SD etc) cards ?
I've not personally done this, but you will probably need to use the low-level FLASH driver IOCTLs to do this correctly.
http://msdn.microsoft.com/en-us/library/aa927166.aspx
I think IOCTL_FMD_RAW_WRITE_BLOCKS looks particularly useful.
-PaulH
Another possibility that may work would be to erase the file normally, then use the defragment APIs to wipe ALL of the freespace on your flash. Since you're wiping everything, it won't be necessary to know exactly where on the disk your file was. But, this will wear out your flash drive more quickly. The C# method is detailed in this blog post: http://blogs.msdn.com/b/jeffrey_wall/archive/2004/09/13/229137.aspx
I get a video feed (mpeg2-ts # 500kb/s) over the network, but I'm uncertain on how to go from here.
The videofeed is now collected in a rather fast growing byte array, and I need a hint on how to feed a video renderer with these bytes. I've used DirectX's AudioVideoPlayback before, but as far as I can se it can only read from files, and I wish to avoid disk usage.
Edit:
I have never worked with DirectShow, so this could be interesting. Maybe using Media Foundation for best forward compatibility? This stuff is brand new so Google dosn't offer me much help...
You should be able to do this with DirectShow. Depending on your exact needs you could render the buffer or let DirectShow handle the networking aspect as well.
I want to make a program that takes an MP3 file and breaks it into many smaller mp3 files based on 1-2 seconds of no sound (silence).
What is the easiest way to do this in c#?
Bass library. Bass has everything you need. It can access, record and edit media streams like mp3s, allowing you to sample the volume at different time points. It has a .net api, so you can use it in c#. Unfortunately it does cost money if you are using it for a commercial application, but they do provide a free non-commercial license.
Sox is a command-line tool which has an option to split an mp3 on n seconds of silence. You could always use the system command to call sox from c#.
Other related links.
Ripping a CD to mp3 in C# - third party component or api out there?
Audio Libraries for MP3 editing
How do I merge/join mp3 files with c#
This code shows a way to make a CD
ripper in C#. There are APIs from some
vendors that allow reading audio CD
tracks but it is also possible to do
it using APIs that allow low level
access to CD drives such as ASPI from
Adaptec or IOCTL control codes. The
latter method is used in this case,
because there is no need to install
any third party software, it is
completely covered by Win32 API
functions.
http://www.codeproject.com/KB/cs/csharpripper.aspx
Splitting the MP3 stream will be difficult to do with any degree of precision. The compressed MP3 data exists as sequential chunks of audio data comprised of many samples. The easiest way to perform this would be to decode the stream either progressively or in its entirety, perform your manipulation, then re-encode it (which as I understand is how most jukebox software does it)
Having a solid knowledge of the file's binary format would be a good place to start. That done, you'll know what silence looks like in the file. You may have to define exactly what silence is. Presuming that, like most audio, it started from an analog source, there's almost certainly some noise buried in the "silence". What will your tolerance for ambient/background noise be?
Once you know what you're looking for, just scan through the file, looking for "it".
Simple ...
A program to do this already exists:
http://mp3splt.sourceforge.net/mp3splt_page/home.php