[FFmpeg-devel] [PATCH] avcodec/ffv1: Allocate unit only when needed and only as large as needed

* [FFmpeg-devel] [PATCH] avcodec/ffv1: Allocate unit only when needed and only as large as needed
@ 2025-04-02  0:51 Michael Niedermayer
  2025-04-04 17:49 ` Michael Niedermayer
  0 siblings, 1 reply; 2+ messages in thread
From: Michael Niedermayer @ 2025-04-02  0:51 UTC (permalink / raw)
  To: FFmpeg development discussions and patches

That is instead of a fixed 65536, we now allocate only as many as there
are pixels.
We also allocate only for the encoder and only when remapping is enabled
and only for 32bit per sample

This should reduce memory consumption, the 2nd array will be
dealt with in a future commit

Signed-off-by: Michael Niedermayer <michael@niedermayer.cc>
---
 libavcodec/ffv1.h    |  2 +-
 libavcodec/ffv1enc.c | 17 +++++++++++++++++
 2 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/libavcodec/ffv1.h b/libavcodec/ffv1.h
index 578b504c9f1..9e71e0709d1 100644
--- a/libavcodec/ffv1.h
+++ b/libavcodec/ffv1.h
@@ -114,7 +114,7 @@ typedef struct FFV1SliceContext {
     struct Unit {
         uint32_t val; //this is unneeded if you accept a dereference on each access
         uint16_t ndx;
-    } unit[4][65536];
+    } *unit[4];
 } FFV1SliceContext;
 
 typedef struct FFV1Context {
diff --git a/libavcodec/ffv1enc.c b/libavcodec/ffv1enc.c
index cd1f6165f75..852eb0c02d2 100644
--- a/libavcodec/ffv1enc.c
+++ b/libavcodec/ffv1enc.c
@@ -1003,12 +1003,22 @@ static av_cold int encode_init_internal(AVCodecContext *avctx)
     s->slice_count = s->max_slice_count;
 
     for (int j = 0; j < s->slice_count; j++) {
+        FFV1SliceContext *sc = &s->slices[j];
+
         for (int i = 0; i < s->plane_count; i++) {
             PlaneContext *const p = &s->slices[j].plane[i];
 
             p->quant_table_index = s->context_model;
             p->context_count     = s->context_count[p->quant_table_index];
         }
+        av_assert0(s->remap_mode >= 0);
+        if (s->remap_mode && s->bits_per_raw_sample == 32) {
+            for (int p = 0; p < 1 + 2*s->chroma_planes + s->transparency ; p++) {
+                sc->unit[p] = av_malloc_array(sc->slice_width, sc->slice_height * sizeof(**sc->unit));
+                if (!sc->unit[p])
+                    return AVERROR(ENOMEM);
+            }
+        }
 
         ff_build_rac_states(&s->slices[j].c, 0.05 * (1LL << 32), 256 - 8);
 
@@ -1808,6 +1818,13 @@ static av_cold int encode_close(AVCodecContext *avctx)
 {
     FFV1Context *const s = avctx->priv_data;
 
+    for (int j = 0; j < s->max_slice_count; j++) {
+        FFV1SliceContext *sc = &s->slices[j];
+
+        for(int p = 0; p<4; p++)
+            av_freep(&sc->unit[p]);
+    }
+
     av_freep(&avctx->stats_out);
     ff_ffv1_close(s);
 
-- 
2.49.0

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