diff --git a/libavcodec/cbs_h264.h b/libavcodec/cbs_h264.h
index a6fe0a6af2..81113f1ad0 100644
--- a/libavcodec/cbs_h264.h
+++ b/libavcodec/cbs_h264.h
@@ -24,6 +24,7 @@
 
 #include "cbs.h"
 #include "cbs_h2645.h"
+#include "cbs_sei.h"
 #include "h264.h"
 
 
@@ -274,21 +275,6 @@ typedef struct H264RawSEIPanScanRect {
     uint16_t pan_scan_rect_repetition_period;
 } H264RawSEIPanScanRect;
 
-typedef struct H264RawSEIUserDataRegistered {
-    uint8_t itu_t_t35_country_code;
-    uint8_t itu_t_t35_country_code_extension_byte;
-    uint8_t     *data;
-    AVBufferRef *data_ref;
-    size_t       data_length;
-} H264RawSEIUserDataRegistered;
-
-typedef struct H264RawSEIUserDataUnregistered {
-    uint8_t uuid_iso_iec_11578[16];
-    uint8_t     *data;
-    AVBufferRef *data_ref;
-    size_t       data_length;
-} H264RawSEIUserDataUnregistered;
-
 typedef struct H264RawSEIRecoveryPoint {
     uint16_t recovery_frame_cnt;
     uint8_t exact_match_flag;
@@ -305,19 +291,6 @@ typedef struct H264RawSEIDisplayOrientation {
     uint8_t display_orientation_extension_flag;
 } H264RawSEIDisplayOrientation;
 
-typedef struct H264RawSEIMasteringDisplayColourVolume {
-    uint16_t display_primaries_x[3];
-    uint16_t display_primaries_y[3];
-    uint16_t white_point_x;
-    uint16_t white_point_y;
-    uint32_t max_display_mastering_luminance;
-    uint32_t min_display_mastering_luminance;
-} H264RawSEIMasteringDisplayColourVolume;
-
-typedef struct H264RawSEIAlternativeTransferCharacteristics {
-    uint8_t preferred_transfer_characteristics;
-} H264RawSEIAlternativeTransferCharacteristics;
-
 typedef struct H264RawSEIPayload {
     uint32_t payload_type;
     uint32_t payload_size;
@@ -326,12 +299,12 @@ typedef struct H264RawSEIPayload {
         H264RawSEIPicTiming pic_timing;
         H264RawSEIPanScanRect pan_scan_rect;
         // H264RawSEIFiller filler -> no fields.
-        H264RawSEIUserDataRegistered user_data_registered;
-        H264RawSEIUserDataUnregistered user_data_unregistered;
+        SEIRawUserDataRegistered user_data_registered;
+        SEIRawUserDataUnregistered user_data_unregistered;
         H264RawSEIRecoveryPoint recovery_point;
         H264RawSEIDisplayOrientation display_orientation;
-        H264RawSEIMasteringDisplayColourVolume mastering_display_colour_volume;
-        H264RawSEIAlternativeTransferCharacteristics
+        SEIRawMasteringDisplayColourVolume mastering_display_colour_volume;
+        SEIRawAlternativeTransferCharacteristics
             alternative_transfer_characteristics;
         struct {
             uint8_t     *data;
diff --git a/libavcodec/cbs_h2645.c b/libavcodec/cbs_h2645.c
index 434322492c..ce58e47a36 100644
--- a/libavcodec/cbs_h2645.c
+++ b/libavcodec/cbs_h2645.c
@@ -253,9 +253,11 @@ static int cbs_h265_payload_extension_present(GetBitContext *gbc, uint32_t paylo
             return err; \
     } while (0)
 
-#define FUNC_NAME(rw, codec, name) cbs_ ## codec ## _ ## rw ## _ ## name
-#define FUNC_H264(rw, name) FUNC_NAME(rw, h264, name)
-#define FUNC_H265(rw, name) FUNC_NAME(rw, h265, name)
+#define FUNC_NAME2(rw, codec, name) cbs_ ## codec ## _ ## rw ## _ ## name
+#define FUNC_NAME1(rw, codec, name) FUNC_NAME2(rw, codec, name)
+#define FUNC_H264(name) FUNC_NAME1(READWRITE, h264, name)
+#define FUNC_H265(name) FUNC_NAME1(READWRITE, h265, name)
+#define FUNC_SEI(name)  FUNC_NAME1(READWRITE, sei,  name)
 
 #define SUBSCRIPTS(subs, ...) (subs > 0 ? ((int[subs + 1]){ subs, __VA_ARGS__ }) : NULL)
 
@@ -356,11 +358,15 @@ static int cbs_h2645_read_more_rbsp_data(GetBitContext *gbc)
         name = name ## _ref->data; \
     } while (0)
 
-#define FUNC(name) FUNC_H264(READWRITE, name)
+#define FUNC(name) FUNC_SEI(name)
+#include "cbs_sei_syntax_template.c"
+#undef FUNC
+
+#define FUNC(name) FUNC_H264(name)
 #include "cbs_h264_syntax_template.c"
 #undef FUNC
 
-#define FUNC(name) FUNC_H265(READWRITE, name)
+#define FUNC(name) FUNC_H265(name)
 #include "cbs_h265_syntax_template.c"
 #undef FUNC
 
@@ -428,11 +434,15 @@ static int cbs_h2645_read_more_rbsp_data(GetBitContext *gbc)
         } \
     } while (0)
 
-#define FUNC(name) FUNC_H264(READWRITE, name)
+#define FUNC(name) FUNC_SEI(name)
+#include "cbs_sei_syntax_template.c"
+#undef FUNC
+
+#define FUNC(name) FUNC_H264(name)
 #include "cbs_h264_syntax_template.c"
 #undef FUNC
 
-#define FUNC(name) FUNC_H265(READWRITE, name)
+#define FUNC(name) FUNC_H265(name)
 #include "cbs_h265_syntax_template.c"
 #undef FUNC
 
diff --git a/libavcodec/cbs_h264_syntax_template.c b/libavcodec/cbs_h264_syntax_template.c
index b65460996b..76ed51cc7b 100644
--- a/libavcodec/cbs_h264_syntax_template.c
+++ b/libavcodec/cbs_h264_syntax_template.c
@@ -700,70 +700,6 @@ static int FUNC(sei_pan_scan_rect)(CodedBitstreamContext *ctx, RWContext *rw,
     return 0;
 }
 
-static int FUNC(sei_user_data_registered)(CodedBitstreamContext *ctx, RWContext *rw,
-                                          H264RawSEIUserDataRegistered *current,
-                                          uint32_t *payload_size)
-{
-    int err, i, j;
-
-    HEADER("User Data Registered ITU-T T.35");
-
-    u(8, itu_t_t35_country_code, 0x00, 0xff);
-    if (current->itu_t_t35_country_code != 0xff)
-        i = 1;
-    else {
-        u(8, itu_t_t35_country_code_extension_byte, 0x00, 0xff);
-        i = 2;
-    }
-
-#ifdef READ
-    if (*payload_size < i) {
-        av_log(ctx->log_ctx, AV_LOG_ERROR,
-               "Invalid SEI user data registered payload.\n");
-        return AVERROR_INVALIDDATA;
-    }
-    current->data_length = *payload_size - i;
-#else
-    *payload_size = i + current->data_length;
-#endif
-
-    allocate(current->data, current->data_length);
-    for (j = 0; j < current->data_length; j++)
-        xu(8, itu_t_t35_payload_byte[i], current->data[j], 0x00, 0xff, 1, i + j);
-
-    return 0;
-}
-
-static int FUNC(sei_user_data_unregistered)(CodedBitstreamContext *ctx, RWContext *rw,
-                                            H264RawSEIUserDataUnregistered *current,
-                                            uint32_t *payload_size)
-{
-    int err, i;
-
-    HEADER("User Data Unregistered");
-
-#ifdef READ
-    if (*payload_size < 16) {
-        av_log(ctx->log_ctx, AV_LOG_ERROR,
-               "Invalid SEI user data unregistered payload.\n");
-        return AVERROR_INVALIDDATA;
-    }
-    current->data_length = *payload_size - 16;
-#else
-    *payload_size = 16 + current->data_length;
-#endif
-
-    for (i = 0; i < 16; i++)
-        us(8, uuid_iso_iec_11578[i], 0x00, 0xff, 1, i);
-
-    allocate(current->data, current->data_length);
-
-    for (i = 0; i < current->data_length; i++)
-        xu(8, user_data_payload_byte[i], current->data[i], 0x00, 0xff, 1, i);
-
-    return 0;
-}
-
 static int FUNC(sei_recovery_point)(CodedBitstreamContext *ctx, RWContext *rw,
                                     H264RawSEIRecoveryPoint *current)
 {
@@ -798,40 +734,6 @@ static int FUNC(sei_display_orientation)(CodedBitstreamContext *ctx, RWContext *
     return 0;
 }
 
-static int FUNC(sei_mastering_display_colour_volume)(CodedBitstreamContext *ctx, RWContext *rw,
-                                                     H264RawSEIMasteringDisplayColourVolume *current)
-{
-    int err, c;
-
-    HEADER("Mastering Display Colour Volume");
-
-    for (c = 0; c < 3; c++) {
-        us(16, display_primaries_x[c], 0, 50000, 1, c);
-        us(16, display_primaries_y[c], 0, 50000, 1, c);
-    }
-
-    u(16, white_point_x, 0, 50000);
-    u(16, white_point_y, 0, 50000);
-
-    u(32, max_display_mastering_luminance, 1, MAX_UINT_BITS(32));
-    u(32, min_display_mastering_luminance, 0, current->max_display_mastering_luminance - 1);
-
-    return 0;
-}
-
-static int FUNC(sei_alternative_transfer_characteristics)(CodedBitstreamContext *ctx,
-                                                          RWContext *rw,
-                                                          H264RawSEIAlternativeTransferCharacteristics *current)
-{
-    int err;
-
-    HEADER("Alternative Transfer Characteristics");
-
-    ub(8, preferred_transfer_characteristics);
-
-    return 0;
-}
-
 static int FUNC(sei_payload)(CodedBitstreamContext *ctx, RWContext *rw,
                              H264RawSEIPayload *current)
 {
@@ -864,11 +766,11 @@ static int FUNC(sei_payload)(CodedBitstreamContext *ctx, RWContext *rw,
         }
         break;
     case H264_SEI_TYPE_USER_DATA_REGISTERED:
-        CHECK(FUNC(sei_user_data_registered)
+        CHECK(FUNC_SEI(sei_user_data_registered)
               (ctx, rw, &current->payload.user_data_registered, &current->payload_size));
         break;
     case H264_SEI_TYPE_USER_DATA_UNREGISTERED:
-        CHECK(FUNC(sei_user_data_unregistered)
+        CHECK(FUNC_SEI(sei_user_data_unregistered)
               (ctx, rw, &current->payload.user_data_unregistered, &current->payload_size));
         break;
     case H264_SEI_TYPE_RECOVERY_POINT:
@@ -880,11 +782,11 @@ static int FUNC(sei_payload)(CodedBitstreamContext *ctx, RWContext *rw,
               (ctx, rw, &current->payload.display_orientation));
         break;
     case H264_SEI_TYPE_MASTERING_DISPLAY_COLOUR_VOLUME:
-        CHECK(FUNC(sei_mastering_display_colour_volume)
+        CHECK(FUNC_SEI(sei_mastering_display_colour_volume)
               (ctx, rw, &current->payload.mastering_display_colour_volume));
         break;
     case H264_SEI_TYPE_ALTERNATIVE_TRANSFER:
-        CHECK(FUNC(sei_alternative_transfer_characteristics)
+        CHECK(FUNC_SEI(sei_alternative_transfer_characteristics)
               (ctx, rw, &current->payload.alternative_transfer_characteristics));
         break;
     default:
diff --git a/libavcodec/cbs_h265.h b/libavcodec/cbs_h265.h
index 15b22bbfd4..d8e93e3bb8 100644
--- a/libavcodec/cbs_h265.h
+++ b/libavcodec/cbs_h265.h
@@ -23,6 +23,7 @@
 #include <stdint.h>
 
 #include "cbs_h2645.h"
+#include "cbs_sei.h"
 #include "hevc.h"
 
 enum {
@@ -596,21 +597,6 @@ typedef struct H265RawSEIPanScanRect {
     uint16_t pan_scan_rect_persistence_flag;
 } H265RawSEIPanScanRect;
 
-typedef struct H265RawSEIUserDataRegistered {
-    uint8_t itu_t_t35_country_code;
-    uint8_t itu_t_t35_country_code_extension_byte;
-    uint8_t     *data;
-    AVBufferRef *data_ref;
-    size_t       data_length;
-} H265RawSEIUserDataRegistered;
-
-typedef struct H265RawSEIUserDataUnregistered {
-    uint8_t uuid_iso_iec_11578[16];
-    uint8_t     *data;
-    AVBufferRef *data_ref;
-    size_t       data_length;
-} H265RawSEIUserDataUnregistered;
-
 typedef struct H265RawSEIRecoveryPoint {
     int16_t recovery_poc_cnt;
     uint8_t exact_match_flag;
@@ -661,24 +647,6 @@ typedef struct H265RawSEITimeCode {
     int32_t  time_offset_value[3];
 } H265RawSEITimeCode;
 
-typedef struct H265RawSEIMasteringDisplayColourVolume {
-    uint16_t display_primaries_x[3];
-    uint16_t display_primaries_y[3];
-    uint16_t white_point_x;
-    uint16_t white_point_y;
-    uint32_t max_display_mastering_luminance;
-    uint32_t min_display_mastering_luminance;
-} H265RawSEIMasteringDisplayColourVolume;
-
-typedef struct H265RawSEIContentLightLevelInfo {
-    uint16_t max_content_light_level;
-    uint16_t max_pic_average_light_level;
-} H265RawSEIContentLightLevelInfo;
-
-typedef struct H265RawSEIAlternativeTransferCharacteristics {
-    uint8_t preferred_transfer_characteristics;
-} H265RawSEIAlternativeTransferCharacteristics;
-
 typedef struct H265RawSEIAlphaChannelInfo {
     uint8_t  alpha_channel_cancel_flag;
     uint8_t  alpha_channel_use_idc;
@@ -697,16 +665,17 @@ typedef struct H265RawSEIPayload {
         H265RawSEIBufferingPeriod buffering_period;
         H265RawSEIPicTiming pic_timing;
         H265RawSEIPanScanRect pan_scan_rect;
-        H265RawSEIUserDataRegistered user_data_registered;
-        H265RawSEIUserDataUnregistered user_data_unregistered;
+        SEIRawUserDataRegistered user_data_registered;
+        SEIRawUserDataUnregistered user_data_unregistered;
         H265RawSEIRecoveryPoint recovery_point;
         H265RawSEIDisplayOrientation display_orientation;
         H265RawSEIActiveParameterSets active_parameter_sets;
         H265RawSEIDecodedPictureHash decoded_picture_hash;
         H265RawSEITimeCode time_code;
-        H265RawSEIMasteringDisplayColourVolume mastering_display;
-        H265RawSEIContentLightLevelInfo content_light_level;
-        H265RawSEIAlternativeTransferCharacteristics
+        SEIRawMasteringDisplayColourVolume
+            mastering_display_colour_volume;
+        SEIRawContentLightLevelInfo content_light_level;
+        SEIRawAlternativeTransferCharacteristics
             alternative_transfer_characteristics;
         H265RawSEIAlphaChannelInfo alpha_channel_info;
         struct {
diff --git a/libavcodec/cbs_h265_syntax_template.c b/libavcodec/cbs_h265_syntax_template.c
index 48fae82d04..e4cc1a9be8 100644
--- a/libavcodec/cbs_h265_syntax_template.c
+++ b/libavcodec/cbs_h265_syntax_template.c
@@ -1808,70 +1808,6 @@ static int FUNC(sei_pan_scan_rect)(CodedBitstreamContext *ctx, RWContext *rw,
     return 0;
 }
 
-static int FUNC(sei_user_data_registered)(CodedBitstreamContext *ctx, RWContext *rw,
-                                          H265RawSEIUserDataRegistered *current,
-                                          uint32_t *payload_size)
-{
-    int err, i, j;
-
-    HEADER("User Data Registered ITU-T T.35");
-
-    u(8, itu_t_t35_country_code, 0x00, 0xff);
-    if (current->itu_t_t35_country_code != 0xff)
-        i = 1;
-    else {
-        u(8, itu_t_t35_country_code_extension_byte, 0x00, 0xff);
-        i = 2;
-    }
-
-#ifdef READ
-    if (*payload_size < i) {
-        av_log(ctx->log_ctx, AV_LOG_ERROR,
-               "Invalid SEI user data registered payload.\n");
-        return AVERROR_INVALIDDATA;
-    }
-    current->data_length = *payload_size - i;
-#else
-    *payload_size = i + current->data_length;
-#endif
-
-    allocate(current->data, current->data_length);
-    for (j = 0; j < current->data_length; j++)
-        xu(8, itu_t_t35_payload_byte[i], current->data[j], 0x00, 0xff, 1, i + j);
-
-    return 0;
-}
-
-static int FUNC(sei_user_data_unregistered)(CodedBitstreamContext *ctx, RWContext *rw,
-                                            H265RawSEIUserDataUnregistered *current,
-                                            uint32_t *payload_size)
-{
-    int err, i;
-
-    HEADER("User Data Unregistered");
-
-#ifdef READ
-    if (*payload_size < 16) {
-        av_log(ctx->log_ctx, AV_LOG_ERROR,
-               "Invalid SEI user data unregistered payload.\n");
-        return AVERROR_INVALIDDATA;
-    }
-    current->data_length = *payload_size - 16;
-#else
-    *payload_size = 16 + current->data_length;
-#endif
-
-    for (i = 0; i < 16; i++)
-        us(8, uuid_iso_iec_11578[i], 0x00, 0xff, 1, i);
-
-    allocate(current->data, current->data_length);
-
-    for (i = 0; i < current->data_length; i++)
-        xu(8, user_data_payload_byte[i], current->data[i], 0x00, 0xff, 1, i);
-
-    return 0;
-}
-
 static int FUNC(sei_recovery_point)(CodedBitstreamContext *ctx, RWContext *rw,
                                     H265RawSEIRecoveryPoint *current)
 {
@@ -2022,55 +1958,6 @@ static int FUNC(sei_time_code)(CodedBitstreamContext *ctx, RWContext *rw,
     return 0;
 }
 
-static int FUNC(sei_mastering_display)(CodedBitstreamContext *ctx, RWContext *rw,
-                                       H265RawSEIMasteringDisplayColourVolume *current)
-{
-    int err, c;
-
-    HEADER("Mastering Display Colour Volume");
-
-    for (c = 0; c < 3; c++) {
-        us(16, display_primaries_x[c], 0, 50000, 1, c);
-        us(16, display_primaries_y[c], 0, 50000, 1, c);
-    }
-
-    u(16, white_point_x, 0, 50000);
-    u(16, white_point_y, 0, 50000);
-
-    u(32, max_display_mastering_luminance,
-      1, MAX_UINT_BITS(32));
-    u(32, min_display_mastering_luminance,
-      0, current->max_display_mastering_luminance - 1);
-
-    return 0;
-}
-
-static int FUNC(sei_content_light_level)(CodedBitstreamContext *ctx, RWContext *rw,
-                                         H265RawSEIContentLightLevelInfo *current)
-{
-    int err;
-
-    HEADER("Content Light Level");
-
-    ub(16, max_content_light_level);
-    ub(16, max_pic_average_light_level);
-
-    return 0;
-}
-
-static int FUNC(sei_alternative_transfer_characteristics)(CodedBitstreamContext *ctx,
-                                                          RWContext *rw,
-                                                          H265RawSEIAlternativeTransferCharacteristics *current)
-{
-    int err;
-
-    HEADER("Alternative Transfer Characteristics");
-
-    ub(8, preferred_transfer_characteristics);
-
-    return 0;
-}
-
 static int FUNC(sei_alpha_channel_info)(CodedBitstreamContext *ctx,
                                         RWContext *rw,
                                         H265RawSEIAlphaChannelInfo *current)
@@ -2180,20 +2067,32 @@ static int FUNC(sei_payload)(CodedBitstreamContext *ctx, RWContext *rw,
                                  &more_data)); \
         break
 
+#define SEI_TYPE_N2(type, prefix_valid, suffix_valid, name) \
+    case HEVC_SEI_TYPE_ ## type: \
+        SEI_TYPE_CHECK_VALID(name, prefix_valid, suffix_valid); \
+        CHECK(FUNC_SEI(sei_ ## name)(ctx, rw, &current->payload.name)); \
+        break
+#define SEI_TYPE_S2(type, prefix_valid, suffix_valid, name) \
+    case HEVC_SEI_TYPE_ ## type: \
+        SEI_TYPE_CHECK_VALID(name, prefix_valid, suffix_valid); \
+        CHECK(FUNC_SEI(sei_ ## name)(ctx, rw, &current->payload.name, \
+                                     &current->payload_size)); \
+        break
+
         SEI_TYPE_E(BUFFERING_PERIOD,         1, 0, buffering_period);
         SEI_TYPE_N(PICTURE_TIMING,           1, 0, pic_timing);
         SEI_TYPE_N(PAN_SCAN_RECT,            1, 0, pan_scan_rect);
-        SEI_TYPE_S(USER_DATA_REGISTERED_ITU_T_T35,
+        SEI_TYPE_S2(USER_DATA_REGISTERED_ITU_T_T35,
                                              1, 1, user_data_registered);
-        SEI_TYPE_S(USER_DATA_UNREGISTERED,   1, 1, user_data_unregistered);
+        SEI_TYPE_S2(USER_DATA_UNREGISTERED,  1, 1, user_data_unregistered);
         SEI_TYPE_N(RECOVERY_POINT,           1, 0, recovery_point);
         SEI_TYPE_N(DISPLAY_ORIENTATION,      1, 0, display_orientation);
         SEI_TYPE_N(ACTIVE_PARAMETER_SETS,    1, 0, active_parameter_sets);
         SEI_TYPE_N(DECODED_PICTURE_HASH,     0, 1, decoded_picture_hash);
         SEI_TYPE_N(TIME_CODE,                1, 0, time_code);
-        SEI_TYPE_N(MASTERING_DISPLAY_INFO,   1, 0, mastering_display);
-        SEI_TYPE_N(CONTENT_LIGHT_LEVEL_INFO, 1, 0, content_light_level);
-        SEI_TYPE_N(ALTERNATIVE_TRANSFER_CHARACTERISTICS,
+        SEI_TYPE_N2(MASTERING_DISPLAY_INFO,  1, 0, mastering_display_colour_volume);
+        SEI_TYPE_N2(CONTENT_LIGHT_LEVEL_INFO,1, 0, content_light_level);
+        SEI_TYPE_N2(ALTERNATIVE_TRANSFER_CHARACTERISTICS,
                                              1, 0, alternative_transfer_characteristics);
         SEI_TYPE_N(ALPHA_CHANNEL_INFO,       1, 0, alpha_channel_info);
 
diff --git a/libavcodec/cbs_sei.h b/libavcodec/cbs_sei.h
new file mode 100644
index 0000000000..95beabf4d7
--- /dev/null
+++ b/libavcodec/cbs_sei.h
@@ -0,0 +1,60 @@
+/*
+ * 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 AVCODEC_CBS_SEI_H
+#define AVCODEC_CBS_SEI_H
+
+#include <stddef.h>
+#include <stdint.h>
+#include "libavutil/buffer.h"
+
+
+typedef struct SEIRawUserDataRegistered {
+    uint8_t      itu_t_t35_country_code;
+    uint8_t      itu_t_t35_country_code_extension_byte;
+    uint8_t     *data;
+    AVBufferRef *data_ref;
+    size_t       data_length;
+} SEIRawUserDataRegistered;
+
+typedef struct SEIRawUserDataUnregistered {
+    uint8_t      uuid_iso_iec_11578[16];
+    uint8_t     *data;
+    AVBufferRef *data_ref;
+    size_t       data_length;
+} SEIRawUserDataUnregistered;
+
+typedef struct SEIRawMasteringDisplayColourVolume {
+    uint16_t display_primaries_x[3];
+    uint16_t display_primaries_y[3];
+    uint16_t white_point_x;
+    uint16_t white_point_y;
+    uint32_t max_display_mastering_luminance;
+    uint32_t min_display_mastering_luminance;
+} SEIRawMasteringDisplayColourVolume;
+
+typedef struct SEIRawContentLightLevelInfo {
+    uint16_t max_content_light_level;
+    uint16_t max_pic_average_light_level;
+} SEIRawContentLightLevelInfo;
+
+typedef struct SEIRawAlternativeTransferCharacteristics {
+    uint8_t preferred_transfer_characteristics;
+} SEIRawAlternativeTransferCharacteristics;
+
+#endif /* AVCODEC_CBS_SEI_H */
diff --git a/libavcodec/cbs_sei_syntax_template.c b/libavcodec/cbs_sei_syntax_template.c
new file mode 100644
index 0000000000..cc900830ae
--- /dev/null
+++ b/libavcodec/cbs_sei_syntax_template.c
@@ -0,0 +1,132 @@
+/*
+ * 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
+ */
+
+static int FUNC(sei_user_data_registered)
+    (CodedBitstreamContext *ctx, RWContext *rw,
+     SEIRawUserDataRegistered *current, uint32_t *payload_size)
+{
+    int err, i, j;
+
+    HEADER("User Data Registered ITU-T T.35");
+
+    u(8, itu_t_t35_country_code, 0x00, 0xff);
+    if (current->itu_t_t35_country_code != 0xff)
+        i = 1;
+    else {
+        u(8, itu_t_t35_country_code_extension_byte, 0x00, 0xff);
+        i = 2;
+    }
+
+#ifdef READ
+    if (*payload_size < i) {
+        av_log(ctx->log_ctx, AV_LOG_ERROR,
+               "Invalid SEI user data registered payload.\n");
+        return AVERROR_INVALIDDATA;
+    }
+    current->data_length = *payload_size - i;
+#else
+    *payload_size = i + current->data_length;
+#endif
+
+    allocate(current->data, current->data_length);
+    for (j = 0; j < current->data_length; j++)
+        xu(8, itu_t_t35_payload_byte[i], current->data[j], 0x00, 0xff, 1, i + j);
+
+    return 0;
+}
+
+static int FUNC(sei_user_data_unregistered)
+    (CodedBitstreamContext *ctx, RWContext *rw,
+     SEIRawUserDataUnregistered *current, uint32_t *payload_size)
+{
+    int err, i;
+
+    HEADER("User Data Unregistered");
+
+#ifdef READ
+    if (*payload_size < 16) {
+        av_log(ctx->log_ctx, AV_LOG_ERROR,
+               "Invalid SEI user data unregistered payload.\n");
+        return AVERROR_INVALIDDATA;
+    }
+    current->data_length = *payload_size - 16;
+#else
+    *payload_size = 16 + current->data_length;
+#endif
+
+    for (i = 0; i < 16; i++)
+        us(8, uuid_iso_iec_11578[i], 0x00, 0xff, 1, i);
+
+    allocate(current->data, current->data_length);
+
+    for (i = 0; i < current->data_length; i++)
+        xu(8, user_data_payload_byte[i], current->data[i], 0x00, 0xff, 1, i);
+
+    return 0;
+}
+
+static int FUNC(sei_mastering_display_colour_volume)
+    (CodedBitstreamContext *ctx, RWContext *rw,
+     SEIRawMasteringDisplayColourVolume *current)
+{
+    int err, c;
+
+    HEADER("Mastering Display Colour Volume");
+
+    for (c = 0; c < 3; c++) {
+        us(16, display_primaries_x[c], 0, 50000, 1, c);
+        us(16, display_primaries_y[c], 0, 50000, 1, c);
+    }
+
+    u(16, white_point_x, 0, 50000);
+    u(16, white_point_y, 0, 50000);
+
+    u(32, max_display_mastering_luminance,
+      1, MAX_UINT_BITS(32));
+    u(32, min_display_mastering_luminance,
+      0, current->max_display_mastering_luminance - 1);
+
+    return 0;
+}
+
+static int FUNC(sei_content_light_level)
+    (CodedBitstreamContext *ctx, RWContext *rw,
+     SEIRawContentLightLevelInfo *current)
+{
+    int err;
+
+    HEADER("Content Light Level");
+
+    ub(16, max_content_light_level);
+    ub(16, max_pic_average_light_level);
+
+    return 0;
+}
+
+static int FUNC(sei_alternative_transfer_characteristics)
+    (CodedBitstreamContext *ctx, RWContext *rw,
+     SEIRawAlternativeTransferCharacteristics *current)
+{
+    int err;
+
+    HEADER("Alternative Transfer Characteristics");
+
+    ub(8, preferred_transfer_characteristics);
+
+    return 0;
+}
diff --git a/libavcodec/h264_metadata_bsf.c b/libavcodec/h264_metadata_bsf.c
index eb1503159b..d7cf58095b 100644
--- a/libavcodec/h264_metadata_bsf.c
+++ b/libavcodec/h264_metadata_bsf.c
@@ -416,7 +416,7 @@ static int h264_metadata_filter(AVBSFContext *bsf, AVPacket *pkt)
         H264RawSEIPayload payload = {
             .payload_type = H264_SEI_TYPE_USER_DATA_UNREGISTERED,
         };
-        H264RawSEIUserDataUnregistered *udu =
+        SEIRawUserDataUnregistered *udu =
             &payload.payload.user_data_unregistered;
 
         for (i = j = 0; j < 32 && ctx->sei_user_data[i]; i++) {
diff --git a/libavcodec/vaapi_encode_h264.c b/libavcodec/vaapi_encode_h264.c
index e52a0e37a4..b577d09caf 100644
--- a/libavcodec/vaapi_encode_h264.c
+++ b/libavcodec/vaapi_encode_h264.c
@@ -96,7 +96,7 @@ typedef struct VAAPIEncodeH264Context {
     H264RawSEIBufferingPeriod      sei_buffering_period;
     H264RawSEIPicTiming            sei_pic_timing;
     H264RawSEIRecoveryPoint        sei_recovery_point;
-    H264RawSEIUserDataUnregistered sei_identifier;
+    SEIRawUserDataUnregistered     sei_identifier;
     char                          *sei_identifier_string;
 
     int aud_needed;
diff --git a/libavcodec/vaapi_encode_h265.c b/libavcodec/vaapi_encode_h265.c
index 3e0af17ea5..a7af763ae4 100644
--- a/libavcodec/vaapi_encode_h265.c
+++ b/libavcodec/vaapi_encode_h265.c
@@ -76,8 +76,8 @@ typedef struct VAAPIEncodeH265Context {
     H265RawSEI   raw_sei;
     H265RawSlice raw_slice;
 
-    H265RawSEIMasteringDisplayColourVolume sei_mastering_display;
-    H265RawSEIContentLightLevelInfo        sei_content_light_level;
+    SEIRawMasteringDisplayColourVolume sei_mastering_display;
+    SEIRawContentLightLevelInfo        sei_content_light_level;
 
     CodedBitstreamContext *cbc;
     CodedBitstreamFragment current_access_unit;
@@ -219,7 +219,8 @@ static int vaapi_encode_h265_write_extra_header(AVCodecContext *avctx,
 
         if (priv->sei_needed & SEI_MASTERING_DISPLAY) {
             sei->payload[i].payload_type = HEVC_SEI_TYPE_MASTERING_DISPLAY_INFO;
-            sei->payload[i].payload.mastering_display = priv->sei_mastering_display;
+            sei->payload[i].payload.mastering_display_colour_volume =
+                priv->sei_mastering_display;
             ++i;
         }
 
@@ -781,7 +782,7 @@ static int vaapi_encode_h265_init_picture_params(AVCodecContext *avctx,
 
             // SEI is needed when both the primaries and luminance are set
             if (mdm->has_primaries && mdm->has_luminance) {
-                H265RawSEIMasteringDisplayColourVolume *mdcv =
+                SEIRawMasteringDisplayColourVolume *mdcv =
                     &priv->sei_mastering_display;
                 const int mapping[3] = {1, 2, 0};
                 const int chroma_den = 50000;
@@ -826,7 +827,7 @@ static int vaapi_encode_h265_init_picture_params(AVCodecContext *avctx,
         if (sd) {
             AVContentLightMetadata *clm =
                 (AVContentLightMetadata *)sd->data;
-            H265RawSEIContentLightLevelInfo *clli =
+            SEIRawContentLightLevelInfo *clli =
                 &priv->sei_content_light_level;
 
             clli->max_content_light_level     = FFMIN(clm->MaxCLL,  65535);
