How to get buffer from drm_prime?

[nyanmisaka]

How to get buffer from drm_prime?

[FH0]

the second linesize should be 960.

04-08 03:43:42.924 I videoFrame.planeCount: 2, format: nv12
04-08 03:43:42.924 I i: 0 linesize: 1920 height: 1080
04-08 03:43:42.926 I i: 1 linesize: 1920 height: 1080

If I copy with hard code, it will be OK.

void onFrame(AVFrame *frame) {
    if (videoSink == nullptr) {
        return;
    }

    auto        fmt = getFormat((AVPixelFormat)frame->format);
    QVideoFrame videoFrame({QSize(frame->width, frame->height), fmt});
    videoFrame.map(QVideoFrame::WriteOnly);
    memcpy(videoFrame.bits(0), frame->data[0], 1920 * 1080);
    memcpy(videoFrame.bits(1), frame->data[1], 1920 * 1080 / 2);
    videoFrame.unmap(); // TODO use drm prime

    emit videoSink->videoFrameChanged(videoFrame);
}

[FH0]

Finally solved by

void onFrame(AVFrame *frame) {
    if (videoSink == nullptr) {
        return;
    }

    auto        fmt = getFormat((AVPixelFormat)frame->format);
    QVideoFrame videoFrame({QSize(frame->width, frame->height), fmt});
    videoFrame.map(QVideoFrame::WriteOnly);
    for (int i = 0; i < videoFrame.planeCount(); i++) {
        memcpy(videoFrame.bits(i), frame->data[i], videoFrame.mappedBytes(i));
    }
    videoFrame.unmap(); // TODO use drm prime

    emit videoSink->videoFrameChanged(videoFrame);
}

But I still don't know how to get buffer from avframe by ffmpeg way.

[nyanmisaka]

@FH0

the second linesize should be 960.

It is a semi-planar format, U and V are interleaved, so the 2nd linesize should be 1920.

1.5: bytes_per_pixel of NV12
Y buf: 1920xAlign(1080)x1.5=3133440 (+128=3133568) //<= calc by MPP runtime
UV buf: 1920xAlign(540)x1.5=1566720

See this func for more info

ffmpeg-rockchip/libavutil/hwcontext_rkmpp.c

Line 192 in ba84e56

static AVBufferRef *rkmpp_drm_pool_alloc(void *opaque, size_t size)