Creating a Motion JPEG frame by frame with variable frame-rate

Question

I'm analyzing a number of solutions to the problem that I have in hand: I'm receiving images from a device and I need to make a video file out of it. However, the images arrive with a somewhat random delay between them and I'm looking for the best way to encode this. I have to create this video frame by frame, and after each frame I must have a new video file with the new frame, replacing the old video file.

I was thinking of fixating the frame-rate a little "faster" than the minimum delay that I might get and just repeat the last frame until a new one arrives, but I guess that this solution is not optimal.

Also, this project is made with Delphi (no, I cannot change that) and I need means to turn these frames into a video file after each frame. I was thinking about using mencoder as an external tool, but I'm reading the documentation and still haven't found an option to make it insert a frame in an already encoded Motion JPEG video file. As my images come in as JPEG, I thought that it would be reasonable to use Motion JPEG, but not even this is certain yet. Also, I don't know if mencoder can be used as a library. It would help a lot if it did.

What would you suggest?

Thermionic

Answer 1

There are some media container formats that support variable frame rate, but I don't think MJPEG is good choice because of the storage overhead. I believe the best way would be to transcode JPEG frames to MP4 format using both I-frames and P-frames.

You can use FFMPEG Delphi/FP header files for the transcoding.

Edit:

The most up to date version of FFMPEG headers can be found at GLScene repository on SourceForge.net. To view the files you can use this link

Splenic

Wow, something like this I desperately need as well. Look carefully at the version numbers of avformat-??.dll. From the link provided you get version 50 while the code specifies 52. Next you need to download swscale-0.dll which you can download from dll-file-download.com/dll-files/…. I'll experiment further, if someone got it working I am interested to hear. – Crampton

Actually the most up to date version that I could find which matches the latest DLLs can be found at GLScene repository on SourceForge.net. The SVN view link is: glscene.svn.sourceforge.net/viewvc/glscene/branches/… – Splenic

Well, avcodec needs ctypes and that needs successive more files which I can't find on sourceforge. Something seems to be missing, any ideas? – Crampton

Goto gtk.org/download/win32.php then download required package. If you are not sure, download all-in-one bundle from ftp.gnome.org/pub/gnome/binaries/win32/gtk+/2.24/… – Splenic

I'm afraid this is not gonna work. It does not contain the required functions like cTypes, cUtils etc. I give up for now. Thanks very much for your time and advice. I'll ask the same question in a more general way. – Crampton

@Arnold: I already use it without any problem. It has more than required modules, so I removed some DLLs also. ;) – Splenic