[FFmpeg-devel] [PATCH v2 65/69] avcodec/mpegvideo: Move arrays owned by main thread to MPVMainContext

[Andreas Rheinhardt]

This commit moves the base pointers of arrays only allocated
by the main thread to MPVMainContext (in case there is a base pointer).

Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt at outlook.com>
---
These arrays are no longer reset in clear_context() because it is
my understanding that there is only one place in the code where
these array pointers could become invalid: in
ff_mpeg_update_thread_context() where one context is copied over
another. Yet only the MPVContext, not the MPVMainContext is copied,
so that these base array pointers are always valid.

Hopefully this can be checked with the testcase from commit
b160fc290cf49b516c5b6ee0730fd9da7fc623b1.

 libavcodec/mpegvideo.c | 23 ++++++++++-------------
 libavcodec/mpegvideo.h |  7 ++++---
 2 files changed, 14 insertions(+), 16 deletions(-)

diff --git a/libavcodec/mpegvideo.c b/libavcodec/mpegvideo.c
index 8debf4d6ab..c8eaafcc1c 100644
--- a/libavcodec/mpegvideo.c
+++ b/libavcodec/mpegvideo.c
@@ -575,7 +575,7 @@ int ff_mpv_init_context_frame(MPVMainContext *m)
         int16_t (*tmp)[2] = av_calloc(mv_table_size, 4 * sizeof(*tmp));
         if (!tmp)
             return AVERROR(ENOMEM);
-        s->p_field_mv_table_base = tmp;
+        m->p_field_mv_table_base = tmp;
         tmp += s->mb_stride + 1;
         for (int i = 0; i < 2; i++) {
             for (int j = 0; j < 2; j++) {
@@ -587,23 +587,23 @@ int ff_mpv_init_context_frame(MPVMainContext *m)
 
     if (s->out_format == FMT_H263) {
         /* cbp values, cbp, ac_pred, pred_dir */
-        if (!(s->coded_block_base = av_mallocz(y_size + (s->mb_height&1)*2*s->b8_stride)) ||
+        if (!(m->coded_block_base = av_mallocz(y_size + (s->mb_height&1)*2*s->b8_stride)) ||
             !(s->cbp_table        = av_mallocz(mb_array_size)) ||
             !(s->pred_dir_table   = av_mallocz(mb_array_size)))
             return AVERROR(ENOMEM);
-        s->coded_block = s->coded_block_base + s->b8_stride + 1;
+        s->coded_block = m->coded_block_base + s->b8_stride + 1;
     }
 
     if (s->h263_pred || s->h263_plus || !s->encoding) {
         /* dc values */
         // MN: we need these for error resilience of intra-frames
-        if (!FF_ALLOCZ_TYPED_ARRAY(s->dc_val_base, yc_size))
+        if (!FF_ALLOCZ_TYPED_ARRAY(m->dc_val_base, yc_size))
             return AVERROR(ENOMEM);
-        s->dc_val[0] = s->dc_val_base + s->b8_stride + 1;
-        s->dc_val[1] = s->dc_val_base + y_size + s->mb_stride + 1;
+        s->dc_val[0] = m->dc_val_base + s->b8_stride + 1;
+        s->dc_val[1] = m->dc_val_base + y_size + s->mb_stride + 1;
         s->dc_val[2] = s->dc_val[1] + c_size;
         for (i = 0; i < yc_size; i++)
-            s->dc_val_base[i] = 1024;
+            m->dc_val_base[i] = 1024;
     }
 
     /* which mb is an intra block,  init macroblock skip table */
@@ -646,13 +646,10 @@ static void clear_context(MPVMainContext *m)
     s->bitstream_buffer = NULL;
     s->allocated_bitstream_buffer_size = 0;
     s->picture          = NULL;
-    s->p_field_mv_table_base = NULL;
     for (int i = 0; i < 2; i++)
         for (int j = 0; j < 2; j++)
             s->p_field_mv_table[i][j] = NULL;
 
-    s->dc_val_base = NULL;
-    s->coded_block_base = NULL;
     s->mbintra_table = NULL;
     s->cbp_table = NULL;
     s->pred_dir_table = NULL;
@@ -761,13 +758,13 @@ void ff_mpv_free_context_frame(MPVMainContext *m)
 
     free_duplicate_contexts(m);
 
-    av_freep(&s->p_field_mv_table_base);
+    av_freep(&m->p_field_mv_table_base);
     for (int i = 0; i < 2; i++)
         for (int j = 0; j < 2; j++)
             s->p_field_mv_table[i][j] = NULL;
 
-    av_freep(&s->dc_val_base);
-    av_freep(&s->coded_block_base);
+    av_freep(&m->dc_val_base);
+    av_freep(&m->coded_block_base);
     av_freep(&s->mbintra_table);
     av_freep(&s->cbp_table);
     av_freep(&s->pred_dir_table);
diff --git a/libavcodec/mpegvideo.h b/libavcodec/mpegvideo.h
index 99d474991a..56c1d8118c 100644
--- a/libavcodec/mpegvideo.h
+++ b/libavcodec/mpegvideo.h
@@ -147,12 +147,10 @@ typedef struct MPVContext {
     Picture *next_picture_ptr;     ///< pointer to the next picture (for bidir pred)
     Picture *current_picture_ptr;  ///< pointer to the current picture
     int last_dc[3];                ///< last DC values for MPEG-1
-    int16_t *dc_val_base;
     int16_t *dc_val[3];            ///< used for MPEG-4 DC prediction, all 3 arrays must be continuous
     const uint8_t *y_dc_scale_table;     ///< qscale -> y_dc_scale table
     const uint8_t *c_dc_scale_table;     ///< qscale -> c_dc_scale table
     const uint8_t *chroma_qscale_table;  ///< qscale -> chroma_qscale (H.263)
-    uint8_t *coded_block_base;
     uint8_t *coded_block;          ///< used for coded block pattern prediction (msmpeg4v3, wmv1)
     int16_t (*ac_val_base)[16];
     int16_t (*ac_val[3])[16];      ///< used for MPEG-4 AC prediction, all 3 arrays must be continuous
@@ -194,7 +192,6 @@ typedef struct MPVContext {
     H263DSPContext h263dsp;
     int f_code;                 ///< forward MV resolution
     int b_code;                 ///< backward MV resolution for B-frames (MPEG-4)
-    int16_t (*p_field_mv_table_base)[2];
     int16_t (*p_mv_table)[2];            ///< MV table (1MV per MB) P-frame encoding
     int16_t (*b_forw_mv_table)[2];       ///< MV table (1MV per MB) forward mode B-frame encoding
     int16_t (*b_back_mv_table)[2];       ///< MV table (1MV per MB) backward mode B-frame encoding
@@ -509,6 +506,10 @@ typedef struct MPVMainContext {
     int slice_context_count;   ///< number of used thread_contexts
     /* The first entry of this array points to the above MPVContext. */
     MPVContext *thread_context[MAX_THREADS];
+
+    int16_t *dc_val_base;
+    uint8_t *coded_block_base;
+    int16_t (*p_field_mv_table_base)[2];
 } MPVMainContext;
 
 /**
-- 
2.32.0