fresnel-fourier iter5b-β Phase 6 commit A: NEW src/codec.{h,c} — pixelformat_for_profile helper

Re-introduce after the iter5b-α' revert. Helper maps VAProfile to V4L2
OUTPUT-side FOURCC, used at CreateConfig in commit B to populate the
previously-dead object_config->pixelformat field. β reads from there
at CreateContext (commit C).

Single source of truth for the profile→pixelformat mapping; mirrors
the per-profile probes in config.c::RequestQueryConfigProfiles
(lines 138-188).

Register codec.c in meson.build sources, codec.h in headers.

Signed-off-by: claude-noether <claude-noether@reauktion.de>

src/codec.c

@@ -0,0 +1,50 @@
+/*
+ * Copyright (C) 2026 claude-noether <claude-noether@reauktion.de>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sub license, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the
+ * next paragraph) shall be included in all copies or substantial portions
+ * of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+ * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.
+ * IN NO EVENT SHALL PRECISION INSIGHT AND/OR ITS SUPPLIERS BE LIABLE FOR
+ * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+ * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+ * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+#include "codec.h"
+
+#include <linux/videodev2.h>
+
+unsigned int pixelformat_for_profile(VAProfile profile)
+{
+	switch (profile) {
+	case VAProfileMPEG2Simple:
+	case VAProfileMPEG2Main:
+		return V4L2_PIX_FMT_MPEG2_SLICE;
+	case VAProfileH264Main:
+	case VAProfileH264High:
+	case VAProfileH264ConstrainedBaseline:
+	case VAProfileH264MultiviewHigh:
+	case VAProfileH264StereoHigh:
+		return V4L2_PIX_FMT_H264_SLICE;
+	case VAProfileHEVCMain:
+		return V4L2_PIX_FMT_HEVC_SLICE;
+	case VAProfileVP8Version0_3:
+		return V4L2_PIX_FMT_VP8_FRAME;
+	case VAProfileVP9Profile0:
+		return V4L2_PIX_FMT_VP9_FRAME;
+	default:
+		return 0;
+	}
+}

src/codec.h

@@ -0,0 +1,48 @@
+/*
+ * Copyright (C) 2026 claude-noether <claude-noether@reauktion.de>
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a
+ * copy of this software and associated documentation files (the
+ * "Software"), to deal in the Software without restriction, including
+ * without limitation the rights to use, copy, modify, merge, publish,
+ * distribute, sub license, and/or sell copies of the Software, and to
+ * permit persons to whom the Software is furnished to do so, subject to
+ * the following conditions:
+ *
+ * The above copyright notice and this permission notice (including the
+ * next paragraph) shall be included in all copies or substantial portions
+ * of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+ * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF
+ * MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NON-INFRINGEMENT.
+ * IN NO EVENT SHALL PRECISION INSIGHT AND/OR ITS SUPPLIERS BE LIABLE FOR
+ * ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT,
+ * TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE
+ * SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ */
+
+#ifndef _CODEC_H_
+#define _CODEC_H_
+
+#include <va/va.h>
+
+/**
+ * pixelformat_for_profile - map a VA-API VAProfile to its V4L2 OUTPUT-side
+ *                            pixel format FOURCC.
+ *
+ * @profile: VAProfile enum value as passed to vaCreateConfig.
+ *
+ * Returns the V4L2_PIX_FMT_* constant that the V4L2 device's OUTPUT_MPLANE
+ * (bitstream-input) queue should be set to in order for the kernel
+ * stateless decoder to dispatch to the right codec_mode. Used at
+ * RequestCreateConfig to populate object_config->pixelformat, and read
+ * from there at RequestCreateContext when committing the OUTPUT format
+ * to the V4L2 device.
+ *
+ * Returns 0 for an unhandled profile; caller is expected to either
+ * fall back to a safe default or refuse to proceed.
+ */
+unsigned int pixelformat_for_profile(VAProfile profile);
+
+#endif /* _CODEC_H_ */

src/meson.build

@@ -49,7 +49,8 @@ sources = [
 	'cap_pool.c',
 	'h265.c',
 	'vp8.c',
-	'vp9.c'
+	'vp9.c',
+	'codec.c'
 ]
 
 headers = [
@@ -74,7 +75,8 @@ headers = [
 	'cap_pool.h',
 	'h265.h',
 	'vp8.h',
-	'vp9.h'
+	'vp9.h',
+	'codec.h'
 ]
 
 includes = [