[FFmpeg-cvslog] sgienc: Use a local RLE encoding function

[Vittorio Giovara]

ffmpeg | branch: master | Vittorio Giovara <vittorio.giovara at gmail.com> | Fri Nov 20 02:17:33 2015 +0100| [59e3f4e598ae381600ef54e1f6e6a8a5270ac245] | committer: Vittorio Giovara

sgienc: Use a local RLE encoding function

SGI RLE encoding is slighlty different than the one provided by rle
module (especially at high bit depth). The pixel count function however
does not change, so it is simply made library-public.

> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=59e3f4e598ae381600ef54e1f6e6a8a5270ac245
---

 libavcodec/rle.c    |   15 +++------------
 libavcodec/rle.h    |   11 +++++++++++
 libavcodec/sgienc.c |   45 ++++++++++++++++++++++++++++++++++++++++-----
 3 files changed, 54 insertions(+), 17 deletions(-)

diff --git a/libavcodec/rle.c b/libavcodec/rle.c
index cbbde93..8a2d922 100644
--- a/libavcodec/rle.c
+++ b/libavcodec/rle.c
@@ -22,16 +22,7 @@
 #include "rle.h"
 #include "libavutil/common.h"
 
-/**
- * Count up to 127 consecutive pixels which are either all the same or
- * all differ from the previous and next pixels.
- * @param start Pointer to the first pixel
- * @param len Maximum number of pixels
- * @param bpp Bytes per pixel
- * @param same 1 if searching for identical pixel values.  0 for differing
- * @return Number of matching consecutive pixels found
- */
-static int count_pixels(const uint8_t *start, int len, int bpp, int same)
+int ff_rle_count_pixels(const uint8_t *start, int len, int bpp, int same)
 {
     const uint8_t *pos;
     int count = 1;
@@ -63,14 +54,14 @@ int ff_rle_encode(uint8_t *outbuf, int out_size, const uint8_t *ptr , int bpp, i
 
     for(x = 0; x < w; x += count) {
         /* see if we can encode the next set of pixels with RLE */
-        if((count = count_pixels(ptr, w-x, bpp, 1)) > 1) {
+        if ((count = ff_rle_count_pixels(ptr, w - x, bpp, 1)) > 1) {
             if(out + bpp + 1 > outbuf + out_size) return -1;
             *out++ = (count ^ xor_rep) + add_rep;
             memcpy(out, ptr, bpp);
             out += bpp;
         } else {
             /* fall back on uncompressed */
-            count = count_pixels(ptr, w-x, bpp, 0);
+            count = ff_rle_count_pixels(ptr, w - x, bpp, 0);
             if(out + bpp*count >= outbuf + out_size) return -1;
             *out++ = (count ^ xor_raw) + add_raw;
 
diff --git a/libavcodec/rle.h b/libavcodec/rle.h
index 00261d3..c967764 100644
--- a/libavcodec/rle.h
+++ b/libavcodec/rle.h
@@ -24,6 +24,17 @@
 #include <stdint.h>
 
 /**
+ * Count up to 127 consecutive pixels which are either all the same or
+ * all differ from the previous and next pixels.
+ * @param start Pointer to the first pixel
+ * @param len Maximum number of pixels
+ * @param bpp Bytes per pixel
+ * @param same 1 if searching for identical pixel values, 0 for differing
+ * @return Number of matching consecutive pixels found
+ */
+int ff_rle_count_pixels(const uint8_t *start, int len, int bpp, int same);
+
+/**
  * RLE compress the row, with maximum size of out_size. Value before repeated bytes is (count ^ xor_rep) + add_rep.
  *                                                      Value before raw bytes is      (count ^ xor_raw) + add_raw.
  * @param outbuf Output buffer
diff --git a/libavcodec/sgienc.c b/libavcodec/sgienc.c
index a449f8c..236c72b 100644
--- a/libavcodec/sgienc.c
+++ b/libavcodec/sgienc.c
@@ -39,6 +39,44 @@ static av_cold int encode_init(AVCodecContext *avctx)
     return 0;
 }
 
+static int sgi_rle_encode(PutByteContext *pbc, const uint8_t *src,
+                          int w, int bpp)
+{
+    int val, count, x, start = bytestream2_tell_p(pbc);
+    void (*bytestream2_put)(PutByteContext *, unsigned int);
+
+    bytestream2_put = bytestream2_put_byte;
+
+    for (x = 0; x < w; x += count) {
+        /* see if we can encode the next set of pixels with RLE */
+        count = ff_rle_count_pixels(src, w - x, bpp, 1);
+        if (count > 1) {
+            if (bytestream2_get_bytes_left_p(pbc) < bpp * 2)
+                return AVERROR_INVALIDDATA;
+
+            val = *src;
+            bytestream2_put(pbc, count);
+            bytestream2_put(pbc, val);
+        } else {
+            int i;
+            /* fall back on uncompressed */
+            count = ff_rle_count_pixels(src, w - x, bpp, 0);
+            if (bytestream2_get_bytes_left_p(pbc) < bpp * (count + 1))
+                return AVERROR_INVALIDDATA;
+
+            bytestream2_put(pbc, count + 0x80);
+            for (i = 0; i < count; i++) {
+                val = src[i];
+                bytestream2_put(pbc, val);
+            }
+        }
+
+        src += count * bpp;
+    }
+
+    return bytestream2_tell_p(pbc) - start;
+}
+
 static int encode_frame(AVCodecContext *avctx, AVPacket *pkt,
                         const AVFrame *frame, int *got_packet)
 {
@@ -110,7 +148,7 @@ FF_ENABLE_DEPRECATION_WARNINGS
     length = SGI_HEADER_SIZE;
     if (avctx->coder_type == FF_CODER_TYPE_RAW)
         length += depth * height * width;
-    else // assume ff_rl_encode() produces at most 2x size of input
+    else // assume sgi_rle_encode() produces at most 2x size of input
         length += tablesize * 2 + depth * height * (2 * width + 1);
 
     if ((ret = ff_alloc_packet(pkt, bytes_per_channel * length)) < 0) {
@@ -166,15 +204,12 @@ FF_ENABLE_DEPRECATION_WARNINGS
                 for (x = 0; x < width; x++)
                     encode_buf[x] = in_buf[depth * x];
 
-                length = ff_rle_encode(pbc.buffer,
-                                       bytestream2_get_bytes_left_p(&pbc),
-                                       encode_buf, 1, width, 0, 0, 0x80, 0);
+                length = sgi_rle_encode(&pbc, encode_buf, width, 1);
                 if (length < 1) {
                     av_free(encode_buf);
                     return -1;
                 }
 
-                bytestream2_skip_p(&pbc, length);
                 bytestream2_put_be32(&tablen_pcb, length);
                 in_buf -= p->linesize[0];
             }