dxva-mpeg2 Allocate slices array dynamically - fixes videos with > 175 slices.

They used to result in images with a black bottom.

sample on team ftp samples/PR471/too_many_slices.ts

Inspired by the vaapi code to reallocate the slices array for each new slice.
Could be more efficient if the array could be preserved for all frames and
freed only at the end of the video, but there doesn't seem to be anywhere
appropriate to free the memory at the end.

Alternative is to allocate the proper size straight away for a new frame,
instead of realloc'ing for each slice.

2 files changed, 85 insertions, 3 deletions

diff --git a/lib/ffmpeg/libavcodec/dxva2_mpeg2.c b/lib/ffmpeg/libavcodec/dxva2_mpeg2.c
index 780542a6c1..9ac2d170b5 100644
--- a/lib/ffmpeg/libavcodec/dxva2_mpeg2.c
+++ b/lib/ffmpeg/libavcodec/dxva2_mpeg2.c
@@ -22,12 +22,12 @@
 
 #include "dxva2_internal.h"
 
-#define MAX_SLICES (SLICE_MAX_START_CODE - SLICE_MIN_START_CODE + 1)
 struct dxva2_picture_context {
     DXVA_PictureParameters pp;
     DXVA_QmatrixData       qm;
     unsigned               slice_count;
-    DXVA_SliceInfo         slice[MAX_SLICES];
+    DXVA_SliceInfo         *slice;
+    unsigned int           slice_alloc;
 
     const uint8_t          *bitstream;
     unsigned               bitstream_size;
@@ -220,6 +220,8 @@ static int start_frame(AVCodecContext *avctx,
     fill_quantization_matrices(avctx, ctx, s, &ctx_pic->qm);
 
     ctx_pic->slice_count    = 0;
+    ctx_pic->slice          = NULL;
+    ctx_pic->slice_alloc    = 0;
     ctx_pic->bitstream_size = 0;
     ctx_pic->bitstream      = NULL;
     return 0;
@@ -232,9 +234,14 @@ static int decode_slice(AVCodecContext *avctx,
     struct dxva2_picture_context *ctx_pic =
         s->current_picture_ptr->hwaccel_picture_private;
     unsigned position;
+    DXVA_SliceInfo* slice;
 
-    if (ctx_pic->slice_count >= MAX_SLICES)
+    slice = av_fast_realloc(ctx_pic->slice,
+                            &ctx_pic->slice_alloc,
+                            (ctx_pic->slice_count + 1) * sizeof(DXVA_SliceInfo));
+    if (!slice)
         return -1;
+    ctx_pic->slice = slice;
 
     if (!ctx_pic->bitstream)
         ctx_pic->bitstream = buffer;
@@ -258,6 +265,7 @@ static int end_frame(AVCodecContext *avctx)
                                      &ctx_pic->pp, sizeof(ctx_pic->pp),
                                      &ctx_pic->qm, sizeof(ctx_pic->qm),
                                      commit_bitstream_and_slice_buffer);
+    av_freep(ctx_pic->slice);
 }
 
 AVHWAccel ff_mpeg2_dxva2_hwaccel = {
diff --git a/lib/ffmpeg/patches/0051-dxva-mpeg2-Allocate-slices-array-dynamically-fixes-v.patch b/lib/ffmpeg/patches/0051-dxva-mpeg2-Allocate-slices-array-dynamically-fixes-v.patch
new file mode 100644
index 0000000000..00a3c7ebbf
--- /dev/null
+++ b/lib/ffmpeg/patches/0051-dxva-mpeg2-Allocate-slices-array-dynamically-fixes-v.patch
@@ -0,0 +1,74 @@
+From 87abcf002b55c8a26b6640ee55a56d3b79dd4740 Mon Sep 17 00:00:00 2001
+From: CrystalP <CrystalP@xbmc.org>
+Date: Wed, 5 Oct 2011 12:38:30 -0400
+Subject: [PATCH 1/6] dxva-mpeg2 Allocate slices array dynamically - fixes videos with > 175 slices.
+ They used to result in images with a black bottom.
+
+sample on team ftp samples/PR471/too_many_slices.ts
+
+Inspired by the vaapi code to reallocate the slices array for each new slice.
+Could be more efficient if the array could be preserved for all frames and
+freed only at the end of the video, but there doesn't seem to be anywhere
+appropriate to free the memory at the end.
+
+Alternative is to allocate the proper size straight away for a new frame,
+instead of realloc'ing for each slice.
+---
+ lib/ffmpeg/libavcodec/dxva2_mpeg2.c |   14 +++++++++++---
+ 1 files changed, 11 insertions(+), 3 deletions(-)
+
+diff --git a/lib/ffmpeg/libavcodec/dxva2_mpeg2.c b/lib/ffmpeg/libavcodec/dxva2_mpeg2.c
+index 780542a..9ac2d17 100644
+--- a/lib/ffmpeg/libavcodec/dxva2_mpeg2.c
++++ b/lib/ffmpeg/libavcodec/dxva2_mpeg2.c
+@@ -22,12 +22,12 @@
+ 
+ #include "dxva2_internal.h"
+ 
+-#define MAX_SLICES (SLICE_MAX_START_CODE - SLICE_MIN_START_CODE + 1)
+ struct dxva2_picture_context {
+     DXVA_PictureParameters pp;
+     DXVA_QmatrixData       qm;
+     unsigned               slice_count;
+-    DXVA_SliceInfo         slice[MAX_SLICES];
++    DXVA_SliceInfo         *slice;
++    unsigned int           slice_alloc;
+ 
+     const uint8_t          *bitstream;
+     unsigned               bitstream_size;
+@@ -220,6 +220,8 @@ static int start_frame(AVCodecContext *avctx,
+     fill_quantization_matrices(avctx, ctx, s, &ctx_pic->qm);
+ 
+     ctx_pic->slice_count    = 0;
++    ctx_pic->slice          = NULL;
++    ctx_pic->slice_alloc    = 0;
+     ctx_pic->bitstream_size = 0;
+     ctx_pic->bitstream      = NULL;
+     return 0;
+@@ -232,9 +234,14 @@ static int decode_slice(AVCodecContext *avctx,
+     struct dxva2_picture_context *ctx_pic =
+         s->current_picture_ptr->hwaccel_picture_private;
+     unsigned position;
++    DXVA_SliceInfo* slice;
+ 
+-    if (ctx_pic->slice_count >= MAX_SLICES)
++    slice = av_fast_realloc(ctx_pic->slice,
++                            &ctx_pic->slice_alloc,
++                            (ctx_pic->slice_count + 1) * sizeof(DXVA_SliceInfo));
++    if (!slice)
+         return -1;
++    ctx_pic->slice = slice;
+ 
+     if (!ctx_pic->bitstream)
+         ctx_pic->bitstream = buffer;
+@@ -258,6 +265,7 @@ static int end_frame(AVCodecContext *avctx)
+                                      &ctx_pic->pp, sizeof(ctx_pic->pp),
+                                      &ctx_pic->qm, sizeof(ctx_pic->qm),
+                                      commit_bitstream_and_slice_buffer);
++    av_freep(ctx_pic->slice);
+ }
+ 
+ AVHWAccel ff_mpeg2_dxva2_hwaccel = {
+-- 
+1.7.3.1.msysgit.0
+