Fix avcodec_align_dimensions to return values suitably aligned for FLV decoding

with SSE and add a avcodec_align_dimensions2 taht returns the stride alignment
requirements independently from doing the width/height padding.

Originally committed as revision 22095 to svn://svn.ffmpeg.org/ffmpeg/trunk

libavcodec/avcodec.h

@@ -1367,7 +1367,7 @@ typedef struct AVCodecContext {
     /**
      * Called at the beginning of each frame to get a buffer for it.
      * If pic.reference is set then the frame will be read later by libavcodec.
-     * avcodec_align_dimensions() should be used to find the required width and
+     * avcodec_align_dimensions2() should be used to find the required width and
      * height, as they normally need to be rounded up to the next multiple of 16.
      * if CODEC_CAP_DR1 is not set then get_buffer() must call
      * avcodec_default_get_buffer() instead of providing buffers allocated by
@@ -3226,7 +3226,19 @@ AVFrame *avcodec_alloc_frame(void);
 int avcodec_default_get_buffer(AVCodecContext *s, AVFrame *pic);
 void avcodec_default_release_buffer(AVCodecContext *s, AVFrame *pic);
 int avcodec_default_reget_buffer(AVCodecContext *s, AVFrame *pic);
+/**
+ * Modifies width and height values so that they will result in a memory
+ * buffer that is acceptable for the codec if you do not use any horizontal
+ * padding.
+ */
 void avcodec_align_dimensions(AVCodecContext *s, int *width, int *height);
+/**
+ * Modifies width and height values so that they will result in a memory
+ * buffer that is acceptable for the codec if you also ensure that all
+ * line sizes are a multiple of the respective linesize_align[i].
+ */
+void avcodec_align_dimensions2(AVCodecContext *s, int *width, int *height,
+                               int linesize_align[4]);
 
 /**
  * Checks if the given dimension of a picture is valid, meaning that all

libavcodec/utils.c

@@ -31,6 +31,7 @@
 #include "libavutil/avstring.h"
 #include "libavutil/integer.h"
 #include "libavutil/crc.h"
+#include "libavutil/pixdesc.h"
 #include "avcodec.h"
 #include "dsputil.h"
 #include "opt.h"
@@ -117,7 +118,7 @@ typedef struct InternalBuffer{
 
 #define INTERNAL_BUFFER_SIZE 32
 
-void avcodec_align_dimensions(AVCodecContext *s, int *width, int *height){
+void avcodec_align_dimensions2(AVCodecContext *s, int *width, int *height, int linesize_align[4]){
     int w_align= 1;
     int h_align= 1;
 
@@ -180,6 +181,36 @@ void avcodec_align_dimensions(AVCodecContext *s, int *width, int *height){
     *height= FFALIGN(*height, h_align);
     if(s->codec_id == CODEC_ID_H264)
         *height+=2; // some of the optimized chroma MC reads one line too much
+
+    linesize_align[0] =
+    linesize_align[1] =
+    linesize_align[2] =
+    linesize_align[3] = STRIDE_ALIGN;
+//STRIDE_ALIGN is 8 for SSE* but this does not work for SVQ1 chroma planes
+//we could change STRIDE_ALIGN to 16 for x86/sse but it would increase the
+//picture size unneccessarily in some cases. The solution here is not
+//pretty and better ideas are welcome!
+#if HAVE_MMX
+    if(s->codec_id == CODEC_ID_SVQ1 || s->codec_id == CODEC_ID_VP5 ||
+       s->codec_id == CODEC_ID_VP6 || s->codec_id == CODEC_ID_VP6F ||
+       s->codec_id == CODEC_ID_VP6A) {
+        linesize_align[0] =
+        linesize_align[1] =
+        linesize_align[2] = 16;
+    }
+#endif
+}
+
+void avcodec_align_dimensions(AVCodecContext *s, int *width, int *height){
+    int chroma_shift = av_pix_fmt_descriptors[s->pix_fmt].log2_chroma_w;
+    int linesize_align[4];
+    int align;
+    avcodec_align_dimensions2(s, width, height, linesize_align);
+    align = FFMAX(linesize_align[0], linesize_align[3]);
+    linesize_align[1] <<= chroma_shift;
+    linesize_align[2] <<= chroma_shift;
+    align = FFMAX3(align, linesize_align[1], linesize_align[2]);
+    *width=FFALIGN(*width, align);
 }
 
 int avcodec_check_dimensions(void *av_log_ctx, unsigned int w, unsigned int h){
@@ -244,7 +275,7 @@ int avcodec_default_get_buffer(AVCodecContext *s, AVFrame *pic){
 
         avcodec_get_chroma_sub_sample(s->pix_fmt, &h_chroma_shift, &v_chroma_shift);
 
-        avcodec_align_dimensions(s, &w, &h);
+        avcodec_align_dimensions2(s, &w, &h, stride_align);
 
         if(!(s->flags&CODEC_FLAG_EMU_EDGE)){
             w+= EDGE_WIDTH*2;
@@ -260,18 +291,6 @@ int avcodec_default_get_buffer(AVCodecContext *s, AVFrame *pic){
 
             unaligned = 0;
             for (i=0; i<4; i++){
-//STRIDE_ALIGN is 8 for SSE* but this does not work for SVQ1 chroma planes
-//we could change STRIDE_ALIGN to 16 for x86/sse but it would increase the
-//picture size unneccessarily in some cases. The solution here is not
-//pretty and better ideas are welcome!
-#if HAVE_MMX
-                if(s->codec_id == CODEC_ID_SVQ1 || s->codec_id == CODEC_ID_VP5 ||
-                   s->codec_id == CODEC_ID_VP6 || s->codec_id == CODEC_ID_VP6F ||
-                   s->codec_id == CODEC_ID_VP6A)
-                    stride_align[i]= 16;
-                else
-#endif
-                stride_align[i] = STRIDE_ALIGN;
                 unaligned |= picture.linesize[i] % stride_align[i];
             }
         } while (unaligned);