CODEWITHSUNDEEP
androidffmpegvideo-encodingandroid-mediacodec
user3265561
user3265561

Reputation: 832

Android MediaCodec change resolution

I am passing the output of a MediaExtractor into a MediaCodec decoder, and then passing the decoder's output buffer to an encoder's input buffer. The problem I have is that I need to reduce the resolution from the 1920x1080 output from the decoder to 1280x720 by the time it comes out of the encoder. I can do this using a Surface, but I am trying to target Android 4.1 so will need to achieve this another way. Does anyone know how to change the resolution of a video file using MediaCodec but in a way that is compatible with 4.1?

Upvotes: 1

Views: 2593

Answers (1)

mstorsjo
mstorsjo

Reputation: 13317

You can use libswscale from libav/ffmpeg, or libyuv, or any other YUV handling library, or write your own downscaling routine - it's not very hard actually.

Basically, when you feed the output from the decoder output buffer into the encoder input buffer, you already can't assume you can do a plain copy, because the two may use different color formats. So to be flexible, your code for copying data already needs to be able to convert any supported decoder output color format into any supported encoder input color format. In this copy step, you can just scale down the data. A trivial nearest neighbor downscale is very simple to implement; better looking scaling require a bit more work.

You don't need to do a full SW decode/encode, you can just use SW to adjust the data in the intermediate copy step. But as fadden pointed out, MediaCodec isn't completely stable prior to 4.3 anyway, so it may still not work on all devices.

Upvotes: 1

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