Adds a new pix fmt function that selects the best dest fmt from among 2 formats to convert to, given a certain src format.

Similar to avcodec_find_best_pix_fmt(), but instead only compares two destination
pix fmts and selects one of these fmts as the best dest format when converting from
a given source format. Also, as opposed to avcodec_find_best_pix_fmt() which supports
only the first 64 defined pixel formats, this supports as input any of the defined
pixel formats.

Also replaces the old function to rely on the new function.

Signed-off-by: Matthew Einhorn <moiein2000@gmail.com>
Signed-off-by: Michael Niedermayer <michaelni@gmx.at>

1 files changed, 36 insertions, 13 deletions

diff --git a/libavcodec/imgconvert.c b/libavcodec/imgconvert.c
index e411b797e0..2339fd0bd2 100644
--- a/libavcodec/imgconvert.c
+++ b/libavcodec/imgconvert.c
@@ -458,10 +458,27 @@ static enum PixelFormat avcodec_find_best_pix_fmt1(int64_t pix_fmt_mask,
 }
 
 enum PixelFormat avcodec_find_best_pix_fmt(int64_t pix_fmt_mask, enum PixelFormat src_pix_fmt,
-                              int has_alpha, int *loss_ptr)
+                                            int has_alpha, int *loss_ptr)
 {
     enum PixelFormat dst_pix_fmt;
-    int loss_mask, i;
+    int i;
+
+    if (loss_ptr) /* all losses count (for backward compatibility) */
+        *loss_ptr = 0;
+
+    dst_pix_fmt = PIX_FMT_NONE; /* so first iteration doesn't have to be treated special */
+    for(i = 0; i< FFMIN(PIX_FMT_NB, 64); i++){
+        if (pix_fmt_mask & (1ULL << i))
+            dst_pix_fmt = avcodec_find_best_pix_fmt2(dst_pix_fmt, i, src_pix_fmt, has_alpha, loss_ptr);
+    }
+    return dst_pix_fmt;
+}
+
+enum PixelFormat avcodec_find_best_pix_fmt2(enum PixelFormat dst_pix_fmt1, enum PixelFormat dst_pix_fmt2,
+                                            enum PixelFormat src_pix_fmt, int has_alpha, int *loss_ptr)
+{
+    enum PixelFormat dst_pix_fmt;
+    int loss1, loss2, loss_order1, loss_order2, i, loss_mask;
     static const int loss_mask_order[] = {
         ~0, /* no loss first */
         ~FF_LOSS_ALPHA,
@@ -469,22 +486,28 @@ enum PixelFormat avcodec_find_best_pix_fmt(int64_t pix_fmt_mask, enum PixelForma
         ~(FF_LOSS_COLORSPACE | FF_LOSS_RESOLUTION),
         ~FF_LOSS_COLORQUANT,
         ~FF_LOSS_DEPTH,
+        ~(FF_LOSS_RESOLUTION | FF_LOSS_DEPTH | FF_LOSS_COLORSPACE | FF_LOSS_ALPHA |
+          FF_LOSS_COLORQUANT | FF_LOSS_CHROMA),
         0,
     };
 
+    loss_mask= loss_ptr?~*loss_ptr:~0; /* use loss mask if provided */
+    dst_pix_fmt = PIX_FMT_NONE;
+    loss1 = avcodec_get_pix_fmt_loss(dst_pix_fmt1, src_pix_fmt, has_alpha) & loss_mask;
+    loss2 = avcodec_get_pix_fmt_loss(dst_pix_fmt2, src_pix_fmt, has_alpha) & loss_mask;
+
     /* try with successive loss */
-    i = 0;
-    for(;;) {
-        loss_mask = loss_mask_order[i++];
-        dst_pix_fmt = avcodec_find_best_pix_fmt1(pix_fmt_mask, src_pix_fmt,
-                                                 has_alpha, loss_mask);
-        if (dst_pix_fmt >= 0)
-            goto found;
-        if (loss_mask == 0)
-            break;
+    for(i = 0;loss_mask_order[i] != 0 && dst_pix_fmt == PIX_FMT_NONE;i++) {
+        loss_order1 = loss1 & loss_mask_order[i];
+        loss_order2 = loss2 & loss_mask_order[i];
+
+        if (loss_order1 == 0 && loss_order2 == 0){ /* use format with smallest depth */
+            dst_pix_fmt = avg_bits_per_pixel(dst_pix_fmt2) < avg_bits_per_pixel(dst_pix_fmt1) ? dst_pix_fmt2 : dst_pix_fmt1;
+        } else if (loss_order1 == 0 || loss_order2 == 0) { /* use format with no loss */
+            dst_pix_fmt = loss_order2 ? dst_pix_fmt1 : dst_pix_fmt2;
+        }
     }
-    return PIX_FMT_NONE;
- found:
+
     if (loss_ptr)
         *loss_ptr = avcodec_get_pix_fmt_loss(dst_pix_fmt, src_pix_fmt, has_alpha);
     return dst_pix_fmt;