From 6f21f5f488f8a82bcb156ff763ddf1737a7fd4a8 Mon Sep 17 00:00:00 2001
From: Kostya Shishkov <kostya.shishkov@gmail.com>
Date: Mon, 27 Nov 2017 17:59:56 +0100
Subject: [PATCH] h263: track first line state too

---
 src/codecs/h263/decoder.rs | 9 ++++++---
 src/codecs/h263/mod.rs     | 5 +++--
 2 files changed, 9 insertions(+), 5 deletions(-)

diff --git a/src/codecs/h263/decoder.rs b/src/codecs/h263/decoder.rs
index 15e18fc..420f6f8 100644
--- a/src/codecs/h263/decoder.rs
+++ b/src/codecs/h263/decoder.rs
@@ -215,8 +215,11 @@ impl H263BaseDecoder {
 
                 if slice.is_at_end(mb_pos) || (slice.needs_check() && mb_pos > 0 && bd.is_slice_end()) {
                     slice = bd.decode_slice_header(&pinfo)?;
-                    //mvi.reset(self.mb_w, mb_x, pinfo.get_mvmode());
-                    //cbpi.reset(self.mb_w);
+                    if !self.is_gob {
+                        mvi.reset(self.mb_w, mb_x, pinfo.get_mvmode());
+                        cbpi.reset(self.mb_w);
+                        sstate.first_line = true;
+                    }
                 }
 
                 let binfo = bd.decode_block_header(&pinfo, &slice, &sstate)?;
@@ -228,7 +231,7 @@ impl H263BaseDecoder {
                         bd.decode_block_intra(&binfo, &sstate, binfo.get_q(), i, (cbp & (1 << (5 - i))) != 0, &mut blk[i])?;
                         if apply_acpred && (binfo.acpred != ACPredMode::None) {
                             let has_b = (i == 1) || (i == 3) || (mb_x > 0);
-                            let has_a = (i == 2) || (i == 3) || (mb_y > 0);
+                            let has_a = (i == 2) || (i == 3) || !sstate.first_line;
                             let (b_mb, b_blk) = if has_b {
                                     if (i == 1) || (i == 3) {
                                         (mb_pos, i - 1)
diff --git a/src/codecs/h263/mod.rs b/src/codecs/h263/mod.rs
index c5d63fc..7e5064e 100644
--- a/src/codecs/h263/mod.rs
+++ b/src/codecs/h263/mod.rs
@@ -120,6 +120,7 @@ pub struct SliceState {
     pub is_iframe:  bool,
     pub mb_x:       usize,
     pub mb_y:       usize,
+    pub first_line: bool,
 }
 
 const SLICE_NO_END: usize = 99999999;
@@ -141,10 +142,10 @@ impl SliceInfo {
 
 impl SliceState {
     pub fn new(is_iframe: bool) -> Self {
-        SliceState { is_iframe: is_iframe, mb_x: 0, mb_y: 0 }
+        SliceState { is_iframe: is_iframe, mb_x: 0, mb_y: 0, first_line: true }
     }
     pub fn next_mb(&mut self) { self.mb_x += 1; }
-    pub fn new_row(&mut self) { self.mb_x = 0; self.mb_y += 1; }
+    pub fn new_row(&mut self) { self.mb_x = 0; self.mb_y += 1; self.first_line = false; }
 }
 
 #[derive(Debug,Clone,Copy)]
-- 
2.39.5