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OK So here is my story:

I am creating an app that requires me to take a couple images and a video and merge them together. At first I had no idea what to use, never heard of ffmpeg or ndk.. After around 5 days of battling NDK, switching to Ubuntu and going crazy with ndk-build commands I finally got FFmpeg to compile using the dolphin-player example. Now that I can run ffmpeg on my computer and android device I have no idea what to do next.

Here are the main questions I have:

  • To use FFmpeg, I saw that I need to use some sort of commands. First off what are these commands, where do I run them?

  • Second of all, Are the commands all I need? By that I mean can i just run my application normally, somewhere in it execute the commands in some way and it will do the rest for me? or do I need some sort of element in the code, for example VideoEncoder instance or something..

  • Third of all, I saw people using NDK to use FFmpeg, Do I have to? Or is it optional? I would like to avoid using C if possible as I don't know it at all..

  • OPTIONAL: Last but not least, Is this the best way of handling what I need to do in my application? If so, can someone guide me in a brief manner of how to use FFmpeg to accomplish said task (mention commands or anything like this)..

I know it's a wall of text but every question is important to me!

Thank you very much stackoverflow community!

Amit Assaraf
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  • I guess you'll have to put the compiled library as a dependency in your project and start calling methods through JNI from it. Is not this the reason you've build the FFmpeg library? What do you understand by commands? – dsafcdsge4rfdse Apr 02 '14 at 20:18

2 Answers2

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1, FFmpeg can be either an app or a set of libraries. If you use it as an app (with an executable binary installed), you can type the commands in a terminal. The app only has limited functions and may not solve your problem. In this case you need to use ffmpeg as libraries and call APIs in your program.

2, To my understanding the commands cannot solve your problem. You need to call ffmpeg APIs. There are a bunch of sample codes for video/image encoding/decoding. You probably also need a container to package the outcome, and ffmpeg libraries can also do that.

3, NDK is preferred by me, since ffmpeg are written in C/C++. There are JAVA wrappers for ffmpeg; if you use them, NDK is not required. However, not all functions in ffmpeg are wrapped well - you may try. If not, then go back to the NDK solution.

4, The simplest way is to decode all your video/images into raw frames, combine them with desired order, and encode them. However in practice this consumes too much memory. The key point then becomes: how can I do the same on the fly? It's not too hard once you reach this step.

Daniel
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  • Can you link me to any ffmpeg wrappers? – Amit Assaraf Apr 03 '14 at 09:54
  • How can I use the dolphin-player code to accompilsh my task? – Amit Assaraf Apr 03 '14 at 12:38
  • dolphin-player decodes a video file and display each frame on the screen. What you need is to (1) decode a few video/image files, (2) combine them, and (3) encode/save in another file. So, dolphin-player can finish step (1), while you still need to do the rest. – Daniel Apr 03 '14 at 14:17
  • I have tried using the following: https://github.com/guardianproject/android-ffmpeg-java Yet after the process of createSlideshowFromImagesAndAudio is complete, the file is never created. If you happen to know why please do comment here.. Meanwhile i will try FMJ – Amit Assaraf Apr 03 '14 at 18:39
  • FMJ is not capable to do what I am asking for. It supports extremely basic functions in FFMpeg for android. – Amit Assaraf Apr 03 '14 at 19:26
  • I still rather see if you can figure out why what I linked behaves as it behaves. Or link me to a different Wrapper. – Amit Assaraf Apr 03 '14 at 19:26
  • Ok I am going to accept your answer and create a new one about suggestions for FFmpeg wrappers. – Amit Assaraf Apr 04 '14 at 13:52
  • @Gopgop Can we use https://github.com/guardianproject/android-ffmpeg-java for video compression? – NitZRobotKoder Feb 02 '15 at 15:03
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I see my answer may no longer relevant to your question but I still put it here as I've recently gone through that very same path and I understand the pain as well as the confusion causing by this matter (setting up NDK using mixed gradle plugin take me 1 day, building FFmpeg takes 2 days and then fail at wtf am I supposed to do next??)

So in short, as @Daniel has pointed out, if you just want to use FFmpeg to run command such ask compressing, cutting, inserting keyframes... then Writing mind's prebuilt FFmpeg Android Java is the easiest way to get FFmpeg running on your app. The downside is since it just run command so it needs to take an input and an output file for the process. See my question here for further clarification.

If you need to do more complex task than this then you have no choice but building the FFmpeg as a library and calling API from it. I've written down step by step instruction that work for me (May 2016). You can see it here:

Please don't ask me to copy the whole thing here as its a very long instruction and it's easier for me to keep 1 source of information up-to-date. I hope this can save someone's keyboard ;).

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