How to get stride and Y plane alignment values for MediaCodec encoder
android, android-mediacodec, encoding
Solution
The problem in a nutshell: there were no CTS tests for video encoding until Android 4.3 (API 18).
As a result, the behavior of `MediaCodec` across different devices was inconsistent, and a few bugs went unnoticed. The EncodeDecodeTest tests exercise the functions you're asking about, and as a result you can reliably feed YUV data to a 4.3+ device (though you still have to runtime-detect whether it wants planar or semi-planar).
For your specific question, the Y plane on older Qualcomm devices needs to be aligned at a 2K boundary, which isn't quite what your code is doing. For 720p video this happens naturally (720*1280 == 450 * 2048), for 176x144 you'd adjust by 1280 to start the UV plane at 26624 instead of 25344. You need to set the absolute alignment within the buffer, not a fixed amount of padding -- use `uvoffset = (width*height + 2047) & ~2047`.
You will need to detect the codec vendor and Android software version, and if it's Qualcomm on pre-4.3 you need to make this adjustment. If your requirements change, and you can target API 18+, these issues go away. (And you can use `Surface` input to `MediaCodec`, which avoids the U/V swap issue, though depending on your needs that may not be useful.)
Problem
There's a few related questions and discussions on this subject: - Mediacodec and camera, color space incorrect - Getting QualComm encoders to work via MediaCodec API - https://groups.google.com/d/msg/android-platform/awaNwgb6EbY/a-YiIOwaL0QJ - https://code.google.com/p/android/issues/detail?id=37769 I am feeding camera preview frames (`NV21` converted to `NV12`) to `MediaCodec` encoder (`NV12` aka `COLOR_FormatYUV420SemiPlanar`). It looks like that on some devices with `QualComm` encoder which are running Android versions less than `4.3` I have to do some input frames processing in order to receive back frame with correct color. On `Sony Xperia ZR` running `Android 4.2.2` I have to add `Y` plane alignment in order to make it working on almost all resolutions. Code above adds `1024` bytes alignment for widths which can not be divided by `32` and `2048` bytes alignment for other resolutions. It makes `MediaCodec` to encode frames properly for all resolutions which can be divided by `16` (except `176x144` for which `UV` plane looks misaligned). ``` int getYPadding() { if (mediaCodecInfo.getName().contains("OMX.qcom") && android.os.Build.VERSION.SDK_INT < 18) { if ((getWidth() % 32) != 0) { return (getWidth()*getHeight()) % 1024; } else { return (getWidth()*getHeight()) % 2048; } } return 0; } ``` I've tried to test this alignment on `LG G2` which is running same `Android 4.2.2` and has `QualComm` encoder, and it looks like it does not working on it correctly. `UV` plane is misaligned (a green stripe at the bottom of the frame). I was not able to calculate the padding which will work for both phones. I also have access to `Sony Xperia Z1` running `Android 4.3` with `QualComm` chipset and it looks like it does not have such problems. Video on every resolution looks fine and `Y` plane does not needs to be aligned anyhow. I understand that it's hardware-related and might be complicated, but since I have to support users running Android prior to `4.3` I have a question. Is it possible to programmatically determine `Y` plane alignment and vertical / horizontal stride values which encoder is expecting for the given color format?