diff --git a/inc/oapv.h b/inc/oapv.h
index 84dc1c2..d0638a1 100644
--- a/inc/oapv.h
+++ b/inc/oapv.h
@@ -532,7 +532,6 @@ struct oapve_param {
     int           full_range_flag;
 };
 
-#define OAPV_CDESC_THREADS_AUTO          0
 /*****************************************************************************
  * automatic assignment of number of threads in creation of encoder & decoder
  *****************************************************************************/
@@ -549,6 +548,8 @@ struct oapve_cdesc {
     int           max_num_frms;
     // max number of threads (or OAPV_CDESC_THREADS_AUTO for auto-assignment)
     int           threads;
+    // flag to disable 'raw bitstream format'
+    int           disable_raw_bitstream_format;
     // encoding parameters
     oapve_param_t param[OAPV_MAX_NUM_FRAMES];
 };
diff --git a/src/oapv.c b/src/oapv.c
index ae70de4..70dee6b 100644
--- a/src/oapv.c
+++ b/src/oapv.c
@@ -1292,8 +1292,9 @@ int oapve_encode(oapve_t eid, oapv_frms_t *ifrms, oapvm_t mid, oapv_bitb_t *bitb
 {
     oapve_ctx_t *ctx;
     oapv_frm_t  *frm;
-    oapv_bs_t   *bs;
+    oapv_bs_t   *bs, bs_pbu_beg;
     int          i, ret;
+    u8          *bs_pos_pbu_beg, *bs_pos_au_beg;
 
     ctx = enc_id_to_ctx(eid);
     oapv_assert_rv(ctx != NULL && bitb->addr && bitb->bsize > 0, OAPV_ERR_INVALID_ARGUMENT);
@@ -1303,11 +1304,10 @@ int oapve_encode(oapve_t eid, oapv_frms_t *ifrms, oapvm_t mid, oapv_bitb_t *bitb
     oapv_bsw_init(bs, bitb->addr, bitb->bsize, NULL);
     oapv_mset(stat, 0, sizeof(oapve_stat_t));
 
-    u8       *bs_pos_au_beg = oapv_bsw_sink(bs); // address syntax of au size
-    u8       *bs_pos_pbu_beg;
-    oapv_bs_t bs_pbu_beg;
-    oapv_bsw_write(bs, 0, 32); // raw bitstream byte size (skip)
-
+    if(!ctx->cdesc.disable_raw_bitstream_format) {
+        bs_pos_au_beg = oapv_bsw_sink(bs); // address syntax of au size
+        oapv_bsw_write(bs, 0, 32); // raw bitstream byte size (skip)
+    }
     oapv_bsw_write(bs, 0x61507631, 32); // signature ('aPv1')
 
     for(i = 0; i < ifrms->num_frms; i++) {
@@ -1382,8 +1382,10 @@ int oapve_encode(oapve_t eid, oapv_frms_t *ifrms, oapvm_t mid, oapv_bitb_t *bitb
         }
     }
 
-    u32 au_size = (u32)((u8 *)oapv_bsw_sink(bs) - bs_pos_au_beg) - 4 /* au_size */;
-    oapv_bsw_write_direct(bs_pos_au_beg, au_size, 32); /* u(32) */
+    if(!ctx->cdesc.disable_raw_bitstream_format) {
+        u32 au_size = (u32)((u8 *)oapv_bsw_sink(bs) - bs_pos_au_beg) - 4;
+        oapv_bsw_write_direct(bs_pos_au_beg, au_size, 32);
+    }
 
     oapv_bsw_deinit(&ctx->bs); /* de-init BSW */
     stat->write = bsw_get_write_byte(&ctx->bs);
diff --git a/src/oapv_param.c b/src/oapv_param.c
index cc62d1a..d9553b2 100644
--- a/src/oapv_param.c
+++ b/src/oapv_param.c
@@ -62,7 +62,6 @@ int oapve_param_default(oapve_param_t *param)
     param->transfer_characteristics = 2; // unspecified transfer characteristics
     param->matrix_coefficients = 2; // unspecified matrix coefficients
     param->full_range_flag = 0; // limited range
-
     return OAPV_OK;
 }