[FFmpeg-devel] [PATCH 2/3] ffv1dec: move header parsing into a separate function

[Lynne]

---
 libavcodec/ffv1dec.c | 64 +++++++++++++++++++++++++++-----------------
 1 file changed, 40 insertions(+), 24 deletions(-)

diff --git a/libavcodec/ffv1dec.c b/libavcodec/ffv1dec.c
index aa988571bc..68a233932d 100644
--- a/libavcodec/ffv1dec.c
+++ b/libavcodec/ffv1dec.c
@@ -548,11 +548,10 @@ static enum AVPixelFormat get_pixel_format(FFV1Context *f)
     return ff_get_format(f->avctx, pix_fmts);
 }
 
-static int read_header(FFV1Context *f)
+static int read_header(FFV1Context *f, RangeCoder *c)
 {
     uint8_t state[CONTEXT_SIZE];
     int context_count = -1; //-1 to avoid warning
-    RangeCoder *const c = &f->slices[0].c;
 
     memset(state, 128, sizeof(state));
 
@@ -898,31 +897,20 @@ static int find_next_slice(AVCodecContext *avctx,
     return 0;
 }
 
-static int decode_frame(AVCodecContext *avctx, AVFrame *rframe,
-                        int *got_frame, AVPacket *avpkt)
+static int decode_header(AVCodecContext *avctx, RangeCoder *c,
+                         uint8_t *buf, size_t buf_size)
 {
-    uint8_t *buf        = avpkt->data;
-    int buf_size        = avpkt->size;
-    FFV1Context *f      = avctx->priv_data;
-    RangeCoder *const c = &f->slices[0].c;
-    int ret, key_frame;
-    uint8_t keystate = 128;
-    uint8_t *buf_end;
-    AVFrame *p;
-
-    ff_progress_frame_unref(&f->last_picture);
-    FFSWAP(ProgressFrame, f->picture, f->last_picture);
-
+    int ret;
+    FFV1Context *f = avctx->priv_data;
 
-    f->avctx = avctx;
-    f->frame_damaged = 0;
+    uint8_t keystate = 128;
     ff_init_range_decoder(c, buf, buf_size);
     ff_build_rac_states(c, 0.05 * (1LL << 32), 256 - 8);
 
     if (get_rac(c, &keystate)) {
-        key_frame = AV_FRAME_FLAG_KEY;
+        f->key_frame = AV_FRAME_FLAG_KEY;
         f->key_frame_ok = 0;
-        if ((ret = read_header(f)) < 0)
+        if ((ret = read_header(f, c)) < 0)
             return ret;
         f->key_frame_ok = 1;
     } else {
@@ -931,7 +919,7 @@ static int decode_frame(AVCodecContext *avctx, AVFrame *rframe,
                    "Cannot decode non-keyframe without valid keyframe\n");
             return AVERROR_INVALIDDATA;
         }
-        key_frame = 0;
+        f->key_frame = 0;
     }
 
     if (f->ac != AC_GOLOMB_RICE) {
@@ -950,6 +938,33 @@ static int decode_frame(AVCodecContext *avctx, AVFrame *rframe,
             return AVERROR_INVALIDDATA;
     }
 
+    return 0;
+}
+
+static int decode_frame(AVCodecContext *avctx, AVFrame *rframe,
+                        int *got_frame, AVPacket *avpkt)
+{
+    uint8_t *buf        = avpkt->data;
+    int buf_size        = avpkt->size;
+    FFV1Context *f      = avctx->priv_data;
+    int ret;
+    uint8_t *buf_end;
+    AVFrame *p;
+
+    /* This is copied onto the first slice's range coder context */
+    RangeCoder c;
+
+    ff_progress_frame_unref(&f->last_picture);
+    FFSWAP(ProgressFrame, f->picture, f->last_picture);
+
+
+    f->avctx = avctx;
+    f->frame_damaged = 0;
+
+    ret = decode_header(avctx, &c, avpkt->data, avpkt->size);
+    if (ret < 0)
+        return ret;
+
     ret = ff_progress_frame_get_buffer(avctx, &f->picture,
                                        AV_GET_BUFFER_FLAG_REF);
     if (ret < 0)
@@ -958,7 +973,7 @@ static int decode_frame(AVCodecContext *avctx, AVFrame *rframe,
     p = f->picture.f;
 
     p->pict_type = AV_PICTURE_TYPE_I; //FIXME I vs. P
-    p->flags     = (p->flags & ~AV_FRAME_FLAG_KEY) | key_frame;
+    p->flags     = (p->flags & ~AV_FRAME_FLAG_KEY) | f->key_frame;
 
     if (f->version < 3 && avctx->field_order > AV_FIELD_PROGRESSIVE) {
         /* we have interlaced material flagged in container */
@@ -1010,9 +1025,10 @@ static int decode_frame(AVCodecContext *avctx, AVFrame *rframe,
         if (i) {
             ff_init_range_decoder(&sc->c, pos, len);
             ff_build_rac_states(&sc->c, 0.05 * (1LL << 32), 256 - 8);
-        } else
+        } else {
+            sc->c = c;
             sc->c.bytestream_end = pos + len;
-
+        }
     }
 
     avctx->execute(avctx,
-- 
2.45.2