protected override Texture LoadStaging(Stream stream)
{
stream.Seek(0, SeekOrigin.Begin);
using var context = new FormatContext(stream);
AVFrame *frame = ffmpeg.av_frame_alloc();
int streamId = ffmpeg.av_find_best_stream(
context.Inner,
AVMediaType.AVMEDIA_TYPE_VIDEO,
-1, -1, null, 0
);
AVCodecContext *codecCtx = context.OpenStream(streamId);
CheckResult(ffmpeg.av_read_frame(context.Inner, context.RecvPacket));
CheckResult(ffmpeg.avcodec_send_packet(codecCtx, context.RecvPacket));
CheckResult(ffmpeg.avcodec_receive_frame(codecCtx, frame));
(uint width, uint height) = ((uint)frame->width, (uint)frame->height);
Texture stagingTexture = _rf.CreateTexture(TextureDescription.Texture2D(
width, height, mipLevels: 1, arrayLayers: 1,
PixelFormat.R8_G8_B8_A8_UNorm, TextureUsage.Staging
));
MappedResource map = _gd.Map(stagingTexture, MapMode.Write);
if (frame->format == (int)AVPixelFormat.AV_PIX_FMT_RGBA)
{
GraphicsUtils.CopyTextureRegion(
src: frame->data[0], 0, 0, 0,
srcRowPitch: (uint)frame->linesize[0],
srcDepthPitch: (uint)frame->linesize[0] * height,
dst: map.Data.ToPointer(), 0, 0, 0,
dstRowPitch: map.RowPitch, dstDepthPitch: map.DepthPitch,
width, height, depth: 1, bytesPerPixel: 4
);
}
else
{
SwsContext *swsContext = ffmpeg.sws_getContext(
frame->width, frame->height, (AVPixelFormat)frame->format,
frame->width, frame->height, AVPixelFormat.AV_PIX_FMT_RGBA,
flags: 0, null, null, null
);
Span <IntPtr> srcPlanes = stackalloc IntPtr[8];
frame->data.CopyPointers(srcPlanes);
Span <int> srcLinesizes = stackalloc int[8];
frame->linesize.CopyTo(srcLinesizes);
Span <IntPtr> dstPlanes = stackalloc IntPtr[4];
dstPlanes[0] = map.Data;
Span <int> dstLinesizes = stackalloc int[4];
dstLinesizes[0] = (int)map.RowPitch;
fixed(IntPtr *pSrcPlanes = &srcPlanes[0])
fixed(IntPtr * pDstPlanes = &dstPlanes[0])
fixed(int *pSrcLinesizes = &srcLinesizes[0])
fixed(int *pDstLinesizes = &dstLinesizes[0])
{
int _ = ffmpeg.sws_scale(swsContext,
(byte **)pSrcPlanes, pSrcLinesizes,
srcSliceY: 0, frame->height,
(byte **)pDstPlanes, pDstLinesizes
);
}
ffmpeg.sws_freeContext(swsContext);
}
_gd.Unmap(stagingTexture);
ffmpeg.av_frame_free(&frame);
ffmpeg.avcodec_free_context(&codecCtx);
return(stagingTexture);
}