diff --git a/libavcodec/utvideoenc.c b/libavcodec/utvideoenc.c
index 68a1a5b..988f821 100644
--- a/libavcodec/utvideoenc.c
+++ b/libavcodec/utvideoenc.c
@@ -27,6 +27,7 @@
 #include "libavutil/intreadwrite.h"
 #include "avcodec.h"
 #include "internal.h"
+#include "bytestream.h"
 #include "put_bits.h"
 #include "dsputil.h"
 #include "mathops.h"
@@ -152,7 +153,7 @@ static av_cold int utvideo_encode_init(AVCodecContext *avctx)
      * Set how many slices are going to be used.
      * Set one slice for now.
      */
-    c->slices = 1;
+    c->slices = 4;

     /* Set compression mode */
     c->compression = COMP_HUFF;
@@ -462,10 +463,9 @@ static int write_huff_codes(uint8_t *src, uint8_t *dst, int dst_size,

 static int encode_plane(AVCodecContext *avctx, uint8_t *src,
                         uint8_t *dst, int step, int stride,
-                        int width, int height, uint8_t **pkt_dst)
+                        int width, int height, PutByteContext *pb)
 {
     UtvideoContext *c        = avctx->priv_data;
-    uint8_t  *where_to_write = *pkt_dst + 256 + (c->slices * 4);
     uint8_t  lengths[256];
     uint32_t counts[256]     = { 0 };

@@ -522,17 +522,15 @@ static int encode_plane(AVCodecContext *avctx, uint8_t *src,
                  */
                 for (i = 0; i < 256; i++) {
                     if (i == symbol)
-                        (*pkt_dst)[i] = 0;
+                        bytestream2_put_byte(pb, 0);
                     else
-                        (*pkt_dst)[i] = 0xFF;
+                        bytestream2_put_byte(pb, 0xFF);
                 }
-                *pkt_dst += 256;

                 /* Write zeroes for lengths */
                 for (i = 0; i < c->slices; i++) {
-                    AV_WL32(*pkt_dst + (4 * i), 0);
+                    bytestream2_put_le32(pb, 0);
                 }
-                *pkt_dst += 4 * c->slices;

                 /* And that's all for that plane folks */
                 return 0;
@@ -550,11 +548,10 @@ static int encode_plane(AVCodecContext *avctx, uint8_t *src,
      * - slice end offsets (gotten from the slice lengths)
      */
     for (i = 0; i < 256; i++) {
-        (*pkt_dst)[i] = lengths[i];
+        bytestream2_put_byte(pb, lengths[i]);
         he[i].len     = lengths[i];
         he[i].sym     = i;
     }
-    *pkt_dst += 256;

     /* Calculate the huffman codes themselves */
     calculate_codes(he);
@@ -574,24 +571,29 @@ static int encode_plane(AVCodecContext *avctx, uint8_t *src,

         slice_len = offset - slice_len;

-        /* Write the offset to the stream */
-        AV_WL32(*pkt_dst + (4 * i), offset);
-
-        /* Byteswap the written data */
+        /* Byteswap the written huffman codes */
         c->dsp.bswap_buf((uint32_t *) c->slice_bits,
                          (uint32_t *) c->slice_bits,
                          slice_len >> 2);

+        /* Write the offset to the stream */
+        bytestream2_put_le32(pb, offset);
+
+        /* Seek to the data part of the packet */
+        bytestream2_seek_p(pb, (4 * ((i + 1) - c->slices)) +
+                           (offset - slice_len), SEEK_CUR);
+
         /* Write the slices' data into the output packet */
-        memcpy(where_to_write, c->slice_bits, slice_len);
+        bytestream2_put_buffer(pb, c->slice_bits, slice_len);

-        where_to_write += slice_len;
+        /* Seek back to the slice offsets */
+        bytestream2_seek_p(pb, (-4 * ((i + 1) - c->slices)) - offset,
+                           SEEK_CUR);

         slice_len = offset;
     }

-    /* Move destination pointer to the start of next plane */
-    *pkt_dst += offset + (4 * c->slices);
+    bytestream2_seek_p(pb, offset, SEEK_CUR);

     return 0;
 }
@@ -600,6 +602,7 @@ static int utvideo_encode_frame(AVCodecContext *avctx, AVPacket *pkt,
                                 const AVFrame *pic, int *got_packet)
 {
     UtvideoContext *c = avctx->priv_data;
+    PutByteContext pb;

     uint32_t frame_info;

@@ -620,6 +623,9 @@ static int utvideo_encode_frame(AVCodecContext *avctx, AVPacket *pkt,

     dst = pkt->data;

+    bytestream2_init_writer(&pb, dst, ((256 + (4 * c->slices) +
+                            (width * height)) * c->planes));
+
     slice_buffer = av_malloc(width * height + FF_INPUT_BUFFER_PADDING_SIZE);

     if (!slice_buffer) {
@@ -651,7 +657,7 @@ static int utvideo_encode_frame(AVCodecContext *avctx, AVPacket *pkt,
         for (i = 0; i < c->planes; i++) {
             ret = encode_plane(avctx, pic->data[0] + rgb_order[i],
                                slice_buffer, c->planes, pic->linesize[0],
-                               width, height, &dst);
+                               width, height, &pb);

             if (ret) {
                 av_log(avctx, AV_LOG_ERROR, "Error encoding plane %d.\n", i);
@@ -662,7 +668,7 @@ static int utvideo_encode_frame(AVCodecContext *avctx, AVPacket *pkt,
     case PIX_FMT_YUV422P:
         for (i = 0; i < c->planes; i++) {
             ret = encode_plane(avctx, pic->data[i], slice_buffer, 1,
-                               pic->linesize[i], width >>!! i, height, &dst);
+                               pic->linesize[i], width >>!! i, height, &pb);

             if (ret) {
                 av_log(avctx, AV_LOG_ERROR, "Error encoding plane %d.\n", i);
@@ -674,7 +680,7 @@ static int utvideo_encode_frame(AVCodecContext *avctx, AVPacket *pkt,
         for (i = 0; i < c->planes; i++) {
             ret = encode_plane(avctx, pic->data[i], slice_buffer, 1,
                                pic->linesize[i], width >>!! i, height >>!! i,
-                               &dst);
+                               &pb);

             if (ret) {
                 av_log(avctx, AV_LOG_ERROR, "Error encoding plane %d.\n", i);
@@ -694,8 +700,7 @@ static int utvideo_encode_frame(AVCodecContext *avctx, AVPacket *pkt,
      * Contains the prediction method.
      */
     frame_info = c->frame_pred << 8;
-    AV_WL32(dst, frame_info);
-    dst += 4;
+    bytestream2_put_le32(&pb, frame_info);

     /*
      * At least currently Ut Video is IDR only.
@@ -705,7 +710,7 @@ static int utvideo_encode_frame(AVCodecContext *avctx, AVPacket *pkt,
     avctx->coded_frame->key_frame = 1;
     avctx->coded_frame->pict_type = AV_PICTURE_TYPE_I;

-    pkt->size   = dst - pkt->data;
+    pkt->size   = bytestream2_tell_p(&pb);
     pkt->flags |= AV_PKT_FLAG_KEY;

     /* Packet should be done */