videotoolbox: add hwcontext support

This adds tons of code for no other benefit than making VideoToolbox
support conform with the new hwaccel API (using hw_device_ctx and
hw_frames_ctx).

Since VideoToolbox decoding does not actually require the user to
allocate frames, the new code does mostly nothing.

One benefit is that ffmpeg_videotoolbox.c can be dropped once generic
hwaccel support for ffmpeg.c is merged from Libav.

Does not consider VDA or VideoToolbox encoding.

Fun fact: the frame transfer functions are copied from vaapi, as the
mapping makes copying generic boilerplate. Mapping itself is not
exported by the VT code, because I don't know how to test.

1 files changed, 54 insertions, 0 deletions

diff --git a/libavutil/hwcontext_videotoolbox.h b/libavutil/hwcontext_videotoolbox.h
new file mode 100644
index 0000000000..7b4de4b7e1
--- /dev/null
+++ b/libavutil/hwcontext_videotoolbox.h
@@ -0,0 +1,54 @@
+/*
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with FFmpeg; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#ifndef AVUTIL_HWCONTEXT_VT_H
+#define AVUTIL_HWCONTEXT_VT_H
+
+#include <stdint.h>
+
+#include <VideoToolbox/VideoToolbox.h>
+
+#include "pixfmt.h"
+
+/**
+ * @file
+ * An API-specific header for AV_HWDEVICE_TYPE_VIDEOTOOLBOX.
+ *
+ * This API currently does not support frame allocation, as the raw VideoToolbox
+ * API does allocation, and FFmpeg itself never has the need to allocate frames.
+ *
+ * If the API user sets a custom pool, AVHWFramesContext.pool must return
+ * AVBufferRefs whose data pointer is a CVImageBufferRef or CVPixelBufferRef.
+ *
+ * Currently AVHWDeviceContext.hwctx and AVHWFramesContext.hwctx are always
+ * NULL.
+ */
+
+/**
+ * Convert a VideoToolbox (actually CoreVideo) format to AVPixelFormat.
+ * Returns AV_PIX_FMT_NONE if no known equivalent was found.
+ */
+enum AVPixelFormat av_map_videotoolbox_format_to_pixfmt(uint32_t cv_fmt);
+
+/**
+ * Convert an AVPixelFormat to a VideoToolbox (actually CoreVideo) format.
+ * Returns 0 if no known equivalent was found.
+ */
+uint32_t av_map_videotoolbox_format_from_pixfmt(enum AVPixelFormat pix_fmt);
+
+#endif /* AVUTIL_HWCONTEXT_VT_H */