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我设法编写了一个类似于 grafika 的 ContinuousCaptureActivity 的视频录制演示（ContinuousCaptureActivity.java 的源代码）。

不同的是，grafika 使用的是硬件编码，而我使用的是软件编码。对于软件编码，我使用 PBO 从 GPU 获取每个视频帧，速度非常快，并将图像数据复制到 ffmpeg，然后进行 h264 编码。

大多数设备的性能是可以接受的，glMapBufferRange() 用时不到5ms，memcpy() 用时不到10ms。

但是在华为mate7的手机上性能较低。glMapBufferRange() 耗时 15~30ms，memcpy() 耗时 25~35ms。

我在 mate7 上测试过正常的 memcpy()，复制正常内存时速度要快得多。

真的很奇怪，谁能帮帮我？

设备信息：

chipset of the phone: HiSilicon Kirin 925
cpu of the phone: Quad-core 1.8 GHz Cortex-A15 & quad-core 1.3 GHz Cortex-A7

在此处查看详细信息：华为 mate 7

pbo代码如下：

    final int buffer_num = 1;
final int pbo_id[] = new int[buffer_num];
private void getPixelFromPBO(int width, int height, boolean isDefaultFb) {
    try {
        long start = System.currentTimeMillis();

        final int pbo_size = width * height * 4;

        if (mFrameNum == 0) {
            GLES30.glGenBuffers(buffer_num, pbo_id, 0);
            Log.d(TAG, "glGenBuffers pbo_id[0]:" + pbo_id[0]);

            GLES30.glBindBuffer(GLES30.GL_PIXEL_PACK_BUFFER, pbo_id[0]);
            //glBufferData creates a new data store for the buffer object currently bound to target
            GLES30.glBufferData(GLES30.GL_PIXEL_PACK_BUFFER, pbo_size, null, GLES30.GL_DYNAMIC_READ);
            GLES30.glBindBuffer(GLES30.GL_PIXEL_PACK_BUFFER, 0);
        }

        GLES30.glPixelStorei(GLES30.GL_PACK_ALIGNMENT, 1);
            checkGlError("glPixelStorei");

        //we need read GL_BACK when the default frame buffer is binded
        //glReadBuffer specifies a color buffer as the source for subsequent glReadPixels, , glCopyTexImage2D, glCopyTexSubImage2D, and glCopyTexSubImage3D commands
        if (isDefaultFb) {
            GLES30.glReadBuffer(GLES30.GL_BACK);
        } else {
            GLES30.glReadBuffer(GLES30.GL_COLOR_ATTACHMENT0);
        }
        checkGlError("glReadBuffer");

        GLES30.glBindBuffer(GLES30.GL_PIXEL_PACK_BUFFER, pbo_id[0]);
        checkGlError("glBindBuffer 1 ");

        long ts = System.currentTimeMillis();
        glReadPixelsPBOJNI(0, 0, width, height, GLES30.GL_RGBA, GLES30.GL_UNSIGNED_BYTE, 0);
        Log.d(TAG, "glReadPixelsPBOJNI took " + (System.currentTimeMillis() - ts) + "ms\n\n\n");
        //GLES30.glReadPixels(0, 0, width, height, GLES30.GL_RGBA, GLES30.GL_UNSIGNED_BYTE, null);
        //glReadPixelsPBOJNI(0, 0, height, width, GLES30.GL_RGBA, GLES30.GL_UNSIGNED_BYTE, 0);
        checkGlError("glReadPixels");
        ts = System.currentTimeMillis();
        ByteBuffer buf = (ByteBuffer) GLES30.glMapBufferRange(
                GLES30.GL_PIXEL_PACK_BUFFER, 0, pbo_size, GLES30.GL_MAP_READ_BIT);
        checkGlError("glMapBufferRange");
        Log.d(TAG, "*****glMapBufferRange took " + (System.currentTimeMillis() - ts) + "ms");

        ts = System.currentTimeMillis();
        cpoyDataToFFmpeg(buf, 1, 1);
        Log.d(TAG, "####cpoyDataToFFmpeg took " + (System.currentTimeMillis() - ts) + "ms\n\n\n");


        GLES30.glUnmapBuffer(GLES30.GL_PIXEL_PACK_BUFFER);
        checkGlError("glUnmapBuffer");
        GLES30.glBindBuffer(GLES30.GL_PIXEL_PACK_BUFFER, 0);
        checkGlError("glBindBuffer 0 ");

    }catch (Exception e) {
        Log.e(TAG, "DO PBO  exp", e);
    }
}
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