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• Android MediaCodec change resolution

  3 mars 2015, par user3265561

  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 ?

• How to subtitle text area coordinates in high resolution images

  18 mars 2015, par Vinay

  I have high resolution images(1920x1080) for subtitles. It is taking more time to display these images as subtitles in the media player we are developing. Once I load the image data into a buffer I need to know if there is standard technique to find the text area where subtitle occurs in the image,say like coordinates (a,b,c,d) inside this area subtitle occurs.How to approach this problem. Using c++,Qt,ff mpeg in our project.

• How can I capture low resolution video on Android reliably across a range of devices ?

  26 octobre 2015, par MisterMat

  Hello Android video experts :)

  I am developing an Android application which allows the user to capture video and upload it to a remote server (it’s more involved than that but the rest of the app is not important). Because of the upload requirement, it is important that the video is of a reasonable size, so not super high resolution. Let’s say a max of 680x480 or 10Mb/minute. This is no problem on Apple devices.

  I have had what can only be described as a complete nightmare trying to capture video at a reasonably low bitrate reliably across a range of Android devices.

  As I understand it there are two ways of capturing video on Android :

  1) Using the Media Recorder/Camera API

  2) Using an Intent to open the cameras video capture application

  Option 1) gives the most flexibility and allows us to easily change the capture resolution. However the Android Camera API is NOT reliable across a range of devices, and I have very good information (including from someone who liaised with Google on this issue) that if you capture video using this API then it will crash on a good 50% of the devices out there. There is a reason that Zoom Camera FX uses an Intent for video capture. Zoom Camera (different app) seems to use Media Recorder, but has lots of bad reviews for video crashing or not working.

  Option 2) works well across a range of devices, as it uses the in built application on the device. The trouble is you have no control whatsoever on the resolution, there is a quality hint on the Intent but the camera app will normally ignore this. My Samsung Galaxy S3 records video by default at about 2Mb/s. This is way too high resolution. The built in application can of course change the resolution, but this relies on action by the user which is difficult to control.

  I understand that I could use a library such as ffmpeg to change the resolution of the video after capture. However this requires me to compile the library for Android, and also I have been informed that in order to legally use the decode/encode codecs on the device you have to pay license fees that amount to about $1 per copy of the app. Since this app will be free to use, this is not an option.

  So that’s where I’m at. I’ve searched long and high for answers, but I can’t figure out how to capture low resolution video reliably using Android.

  Any help very much appreciated !

  Matthew