diff --git a/smpte/291.h b/smpte/291.h
new file mode 100644
index 0000000..798b56f
--- /dev/null
+++ b/smpte/291.h
@@ -0,0 +1,151 @@
+/*****************************************************************************
+ * 291.h: SMPTE 291 Ancillary Data Packet and Space Formatting
+ *****************************************************************************
+ * Copyright (C) 2016 OpenHeadend
+ *
+ * Authors: Christophe Massiot <cmassiot@openheadend.tv>
+ *
+ * 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, sublicense, 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 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 NONINFRINGEMENT.
+ * IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS 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.
+ *****************************************************************************/
+
+/*
+ * Normative references:
+ *  - SMPTE 291
+ *  - SMPTE RP-291
+ */
+
+#ifndef __BITSTREAM_SMPTE_291_H__
+#define __BITSTREAM_SMPTE_291_H__
+
+#include <stdint.h>   /* uint8_t, uint16_t, etc... */
+#include <stdbool.h>  /* bool */
+
+#ifdef __cplusplus
+extern "C"
+{
+#endif
+
+/*****************************************************************************
+ * SMPTE 291 ancillary data (8-bit mode only)
+ *****************************************************************************/
+#define S291_HEADER_SIZE            6
+#define S291_FOOTER_SIZE            1
+
+#define S291_ADF1                   0x00
+#define S291_ADF2                   0xff
+#define S291_ADF3                   0xff
+
+/* SMPTE 2016 */
+#define S291_AFD_DID                0x41
+#define S291_AFD_SDID               0x05
+#define S291_PAN_SCAN_DID           0x41
+#define S291_PAN_SCAN_SDID          0x06
+
+/* SMPTE 2010 */
+#define S291_SCTE104_DID            0x41
+#define S291_SCTE104_SDID           0x07
+
+/* OP-47 / SMPTE RDD-8 */
+#define S291_OP47SDP_DID            0x43
+#define S291_OP47SDP_SDID           0x02
+#define S291_OP47MP_DID             0x43
+#define S291_OP47MP_SDID            0x03
+
+/* SMPTE 12M */
+#define S291_ATC_DID                0x60
+#define S291_ATC_SDID               0x60
+
+/* SMPTE 334 */
+#define S291_CEA708_DID             0x61
+#define S291_CEA708_SDID            0x01
+#define S291_CEA608_DID             0x61
+#define S291_CEA608_SDID            0x02
+
+/* SMPTE RP-207 */
+#define S291_PROGDESC_DID           0x62
+#define S291_PROGDESC_SDID          0x01
+
+/* SMPTE 334 */
+#define S291_DATABROADCAST_DID      0x62
+#define S291_DATABROADCAST_SDID     0x02
+
+/* SMPTE RP-208 (legacy) */
+#define S291_SMPTEVBI_DID           0x62
+#define S291_SMPTEVBI_SDID          0x03
+
+static inline void s291_set_did(uint8_t *p_s291, uint8_t i_did)
+{
+    p_s291[3] = i_did;
+}
+
+static inline uint8_t s291_get_did(const uint8_t *p_s291)
+{
+    return p_s291[3];
+}
+
+static inline void s291_set_sdid(uint8_t *p_s291, uint8_t i_sdid)
+{
+    p_s291[4] = i_sdid;
+}
+
+static inline uint8_t s291_get_sdid(const uint8_t *p_s291)
+{
+    return p_s291[4];
+}
+
+static inline void s291_set_data_mode(uint8_t *p_s291, uint8_t i_data_mode)
+{
+    p_s291[5] &= ~0x60;
+    p_s291[5] |= (i_data_mode << 5) & 0x60;
+}
+
+#define s291_set_dbn s291_set_sdid
+#define s291_get_dbn s291_get_sdid
+
+static inline void s291_set_dc(uint8_t *p_s291, uint8_t i_dc)
+{
+    p_s291[5] = i_dc;
+}
+
+static inline uint8_t s291_get_dc(const uint8_t *p_s291)
+{
+    return p_s291[5];
+}
+
+static inline uint8_t *s291_get_udw(const uint8_t *p_s291)
+{
+    return (uint8_t *)&p_s291[6];
+}
+
+static inline bool s291_check_crc(const uint8_t *p_s291)
+{
+    uint8_t i_crc = 0;
+    uint8_t i_dc = s291_get_dc(p_s291);
+    int i;
+    for (i = 3; i < i_dc + S291_HEADER_SIZE; i++)
+        i_crc += p_s291[i];
+    return i_crc == p_s291[i];
+}
+
+#ifdef __cplusplus
+}
+#endif
+
+#endif