diff --git a/libavcodec/avs3.h b/libavcodec/avs3.h
new file mode 100644
index 0000000000..4189d9b583
--- /dev/null
+++ b/libavcodec/avs3.h
@@ -0,0 +1,118 @@
+/*
+ *  AVS3 related definitions
+ *
+ * Copyright (C) 2020 Huiwen Ren, <hwrenx@gmail.com>
+ *
+ * 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_AVS3_H
+#define AVCODEC_AVS3_H
+
+#define AVS3_NAL_START_CODE          0x010000
+#define AVS3_SEQ_START_CODE          0xB0
+#define AVS3_SEQ_END_CODE            0xB1
+#define AVS3_USER_DATA_START_CODE    0xB2
+#define AVS3_INTRA_PIC_START_CODE    0xB3
+#define AVS3_UNDEF_START_CODE        0xB4
+#define AVS3_EXTENSION_START_CODE    0xB5
+#define AVS3_INTER_PIC_START_CODE    0xB6
+#define AVS3_VIDEO_EDIT_CODE         0xB7
+#define AVS3_FIRST_SLICE_START_CODE  0x00
+#define AVS3_PROFILE_BASELINE_MAIN   0x20
+#define AVS3_PROFILE_BASELINE_MAIN10 0x22
+
+#define AVS3_ISPIC(x) ((x) == AVS3_INTRA_PIC_START_CODE || (x) == AVS3_INTER_PIC_START_CODE)
+#define AVS3_ISUNIT(x) ((x) == AVS3_SEQ_START_CODE || AVS3_ISPIC(x))
+
+#include "libavutil/avutil.h"
+#include "libavutil/pixfmt.h"
+#include "libavutil/rational.h"
+
+static const AVRational ff_avs3_frame_rate_tab[16] = {
+    { 0    , 0   }, // forbid
+    { 24000, 1001},
+    { 24   , 1   },
+    { 25   , 1   },
+    { 30000, 1001},
+    { 30   , 1   },
+    { 50   , 1   },
+    { 60000, 1001},
+    { 60   , 1   },
+    { 100  , 1   },
+    { 120  , 1   },
+    { 200  , 1   },
+    { 240  , 1   },
+    { 300  , 1   },
+    { 0    , 0   }, // reserved
+    { 0    , 0   }  // reserved
+};
+
+static const int ff_avs3_color_primaries_tab[10] = {
+    AVCOL_PRI_RESERVED0   ,    // 0
+    AVCOL_PRI_BT709       ,    // 1
+    AVCOL_PRI_UNSPECIFIED ,    // 2
+    AVCOL_PRI_RESERVED    ,    // 3
+    AVCOL_PRI_BT470M      ,    // 4
+    AVCOL_PRI_BT470BG     ,    // 5
+    AVCOL_PRI_SMPTE170M   ,    // 6
+    AVCOL_PRI_SMPTE240M   ,    // 7
+    AVCOL_PRI_FILM        ,    // 8
+    AVCOL_PRI_BT2020           // 9
+};
+
+static const int ff_avs3_color_transfer_tab[15] = {
+    AVCOL_TRC_RESERVED0    , // 0
+    AVCOL_TRC_BT709        , // 1
+    AVCOL_TRC_UNSPECIFIED  , // 2
+    AVCOL_TRC_RESERVED     , // 3
+    AVCOL_TRC_GAMMA22      , // 4
+    AVCOL_TRC_GAMMA28      , // 5
+    AVCOL_TRC_SMPTE170M    , // 6
+    AVCOL_TRC_SMPTE240M    , // 7
+    AVCOL_TRC_LINEAR       , // 8
+    AVCOL_TRC_LOG          , // 9
+    AVCOL_TRC_LOG_SQRT     , // 10
+    AVCOL_TRC_BT2020_12    , // 11
+    AVCOL_TRC_SMPTE2084    , // 12
+    AVCOL_TRC_UNSPECIFIED  , // 13
+    AVCOL_TRC_ARIB_STD_B67   // 14
+};
+
+static const int ff_avs3_color_matrix_tab[12] = {
+    AVCOL_SPC_RESERVED     , // 0
+    AVCOL_SPC_BT709        , // 1
+    AVCOL_SPC_UNSPECIFIED  , // 2
+    AVCOL_SPC_RESERVED     , // 3
+    AVCOL_SPC_FCC          , // 4
+    AVCOL_SPC_BT470BG      , // 5
+    AVCOL_SPC_SMPTE170M    , // 6
+    AVCOL_SPC_SMPTE240M    , // 7
+    AVCOL_SPC_BT2020_NCL   , // 8
+    AVCOL_SPC_BT2020_CL    , // 9
+    AVCOL_SPC_UNSPECIFIED  , // 10
+    AVCOL_SPC_UNSPECIFIED    // 11
+};
+
+static const enum AVPictureType ff_avs3_image_type[4] = {
+    AV_PICTURE_TYPE_NONE,
+    AV_PICTURE_TYPE_I,
+    AV_PICTURE_TYPE_P,
+    AV_PICTURE_TYPE_B
+};
+
+#endif /* AVCODEC_AVS3_H */