[vlc-devel] [RFC PATCH] input: decoder: optimize dpb_size of H264

[Zhao Zhili]

---
 src/input/decoder.c | 120
++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 120 insertions(+)
diff --git a/src/input/decoder.c b/src/input/decoder.c
index 400464d..2283503 100644
--- a/src/input/decoder.c
+++ b/src/input/decoder.c
@@ -370,6 +370,80 @@ static int aout_update_format( decoder_t *p_dec )
     return 0;
 }

+/* copy and paste from modules/packetizer/h264_nal.c
+ */
+static bool h264_get_profile_level(const es_format_t *p_fmt, int
*pi_profile,
+                            int *pi_level, uint8_t *pi_nal_length_size)
+{
+    uint8_t *p = (uint8_t*)p_fmt->p_extra;
+    if(p_fmt->i_extra < 8)
+        return false;
+
+    /* Check the profile / level */
+    if (p[0] == 1 && p_fmt->i_extra >= 12)
+    {
+        if (pi_nal_length_size)
+            *pi_nal_length_size = 1 + (p[4]&0x03);
+        p += 8;
+    }
+    else if(!p[0] && !p[1]) /* FIXME: WTH is setting AnnexB data here ? */
+    {
+        if (!p[2] && p[3] == 1)
+            p += 4;
+        else if (p[2] == 1)
+            p += 3;
+        else
+            return false;
+    }
+    else return false;
+
+    if ( ((*p++)&0x1f) != 7) return false;
+
+    if (pi_profile)
+        *pi_profile = p[0];
+
+    if (pi_level)
+        *pi_level = p[2];
+
+    return true;
+}
+
+static inline int h264_get_max_dpb_mbs(int level)
+{
+    int max_dpb_mbs = -1;
+    switch (level)
+    {
+    case 30:
+        max_dpb_mbs = 8100;
+        break;
+    case 31:
+        max_dpb_mbs = 18000;
+        break;
+    case 32:
+        max_dpb_mbs = 20480;
+        break;
+    case 40:
+    case 41:
+        max_dpb_mbs = 32768;
+        break;
+    case 42:
+        max_dpb_mbs = 34816;
+        break;
+    case 50:
+        max_dpb_mbs = 110400;
+        break;
+    case 51:
+    case 52:
+        max_dpb_mbs = 184320;
+        break;
+    default:
+        max_dpb_mbs = -1;
+        break;
+    }
+
+    return max_dpb_mbs;
+}
+
 static int vout_update_format( decoder_t *p_dec )
 {
     decoder_owner_sys_t *p_owner = p_dec->p_owner;
@@ -462,8 +536,54 @@ static int vout_update_format( decoder_t *p_dec )
         unsigned dpb_size;
         switch( p_dec->fmt_in.i_codec )
         {
+        // TODO: optimize dpb_size as H264
         case VLC_CODEC_HEVC:
+            dpb_size = 18;
+            break;
         case VLC_CODEC_H264:
+            {
+#define H264_MAX_DPB_SIZE   18
+                dpb_size = H264_MAX_DPB_SIZE;
+
+                int profile = -1;
+                int level = -1;
+
+                profile = p_dec->fmt_in.i_profile;
+                level = p_dec->fmt_in.i_level;
+                if( profile == -1 || level == -1 )
+                {
+                    if( h264_get_profile_level( &p_dec->fmt_in, &profile,
&level, NULL ) == false )
+                    {
+                        msg_Warn( p_dec, "get profile and level failed" );
+                        break;
+                    }
+                }
+                msg_Dbg( p_dec, "H264 profile %d, level %d", profile,
level );
+
+#define PROFILE_H264_MAIN                 77
+#define PROFILE_H264_HIGH                 100
+                if( profile != PROFILE_H264_MAIN && profile !=
PROFILE_H264_HIGH )
+                    break;
+
+                int max_dpb_mbs = h264_get_max_dpb_mbs( level );
+                if( max_dpb_mbs <= 0 )
+                    break;
+
+                int pic_width_in_mbs = fmt.i_visible_width / 16;
+                int frame_height_in_mbs = fmt.i_visible_height / 16;
+                if( pic_width_in_mbs <= 0 || frame_height_in_mbs <= 0 )
+                    break;
+
+                dpb_size = max_dpb_mbs / (pic_width_in_mbs *
frame_height_in_mbs);
+                if( dpb_size < 5 )
+                    dpb_size = 5;
+                else if( dpb_size > H264_MAX_DPB_SIZE )
+                    dpb_size = H264_MAX_DPB_SIZE;
+
+                msg_Dbg( p_dec, "width %d, height %d, dpb_size %d",
+                        fmt.i_visible_width, fmt.i_visible_height,
dpb_size );
+            }
+            break;
         case VLC_CODEC_DIRAC: /* FIXME valid ? */
             dpb_size = 18;
             break;
-- 
2.7.4
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