Ticket #4752: h264_length.diff

libs/libmythtv/mpeg/h264utils.cpp

@@ -42 +42 @@
 extern "C" {
 // from libavcodec
 extern const uint8_t *ff_find_start_code(const uint8_t * p, const uint8_t *end, uint32_t * state);
+#include "avcodec.h"
 }
 
 namespace H264
@@ -62 +63 @@
 
     first_NAL_byte = H264::NALUnitType::UNKNOWN;
 
+    log2_max_frame_num = -1;
+    frame_num = 0;
+    prev_frame_num = -1;
+
     saw_AU_delimiter = false;
     saw_first_VCL_NAL_unit = false;
     saw_sps = false;
+    separate_colour_plane_flag = false;
+    frame_mbs_only_flag = true;
+    new_VLC_NAL = false;
 
     did_evaluate_once = false;
     keyframe = false;
@@ -127 +135 @@
     // stage 3: did we see the AU's first VCL NAL unit yet?
     if (!saw_first_VCL_NAL_unit && NALUnitType::IsVCLType(new_NAL_type))
     {
-        saw_first_VCL_NAL_unit = true;
+        saw_first_VCL_NAL_unit = new_VLC_NAL;
         saw_AU_delimiter = false;
         state_changed = true;
         if (saw_sps)
@@ -154 +162 @@
         if ((sync_accumulator & 0xffffff00) == 0x00000100)
         {
             uint8_t k = *(local_bytes-1);
+            uint8_t NAL_type = k & 0x1f;
             sync_stream_offset = stream_offset;
             keyframe = false;
 
+            if (NAL_type == NALUnitType::SPS ||
+                NAL_type == NALUnitType::SLICE ||
+                NAL_type == NALUnitType::SLICE_DPA) {
+            /*
+              bitstream buffer, must be FF_INPUT_BUFFER_PADDING_SIZE
+              bytes larger then the actual read bits
+            */
+                if (local_bytes + 20 + FF_INPUT_BUFFER_PADDING_SIZE <
+                    local_bytes_end) {
+                    init_get_bits(&gb, local_bytes,
+                                  8 * (local_bytes_end - local_bytes));
+
+                    if (NAL_type == NALUnitType::SPS)
+                        decode_SPS(&gb);
+                    else
+                        decode_Header(&gb);
+                }
+
+            }
+            else if (NAL_type == NALUnitType::SLICE_IDR)
+                frame_num = 0;
+
             KeyframePredicate(k);
             first_NAL_byte = k;
 
@@ -175 +206 @@
     return saw_first_VCL_NAL_unit;
 }
 
+void KeyframeSequencer::decode_Header(GetBitContext * gb)
+{
+    uint       first_mb_in_slice;
+    uint       slice_type;
+    uint       pic_parameter_set_id;
+    bool       field_pic_flag;
+    bool       bottom_field_flag;
+
+    if (log2_max_frame_num < 1)
+    {
+        std::cerr
+            << "KeyframeSequencer::decode_Header: SPS has not been parsed!\n";
+        return;
+    }
+
+    new_VLC_NAL = false;
+
+    prev_frame_num = frame_num;
+
+    first_mb_in_slice = get_ue_golomb(gb);
+    slice_type = get_ue_golomb(gb);
+
+    pic_parameter_set_id = get_ue_golomb(gb);
+    if (pic_parameter_set_id != prev_pic_parameter_set_id) {
+        new_VLC_NAL = true;
+        prev_pic_parameter_set_id = pic_parameter_set_id;
+    }
+
+    if (separate_colour_plane_flag)
+        get_bits(gb, 2);  // colour_plane_id
+
+    frame_num = get_bits(gb, log2_max_frame_num);
+
+    if (frame_mbs_only_flag)
+        new_VLC_NAL = true;
+    else
+    {
+        /* From section 7.3.3 Slice header syntax
+          if (!frame_mbs_only_flag) {
+            field_pic_flag = get_bits1(gb);
+            if (field_pic_flag)
+              bottom_field_flag = get_bits1(gb);
+          }
+         */
+
+#if 0
+        new_VLC_NAL = get_bits1(gb) ? !get_bits1(gb) : true;
+#else
+        field_pic_flag = get_bits1(gb);
+        if (field_pic_flag != prev_field_pic_flag) {
+            new_VLC_NAL = true;
+            prev_field_pic_flag = field_pic_flag;
+        }
+
+        if (field_pic_flag) {
+            bottom_field_flag = get_bits1(gb);
+            if (bottom_field_flag != prev_bottom_field_flag) {
+                new_VLC_NAL = !bottom_field_flag;
+                prev_bottom_field_flag = bottom_field_flag;
+            }
+        }
+#endif
+    }
+}
+
+/*
+ * libavcodec used for example
+ */
+void KeyframeSequencer::decode_SPS(GetBitContext * gb)
+{
+    int profile_idc, chroma_format_idc;
+
+    profile_idc = get_bits(gb, 8); // profile_idc
+    get_bits1(gb);   // constraint_set0_flag
+    get_bits1(gb);   // constraint_set1_flag
+    get_bits1(gb);   // constraint_set2_flag
+    get_bits1(gb);   // constraint_set3_flag
+    get_bits(gb, 4); // reserved
+    get_bits(gb, 8); // level_idc
+    get_ue_golomb(gb);  // sps_id
+
+    if(profile_idc >= 100){ // high profile
+        if((chroma_format_idc = get_ue_golomb(gb)) == 3) // chroma_format_idc
+            separate_colour_plane_flag = (get_bits1(gb) == 1);
+        get_ue_golomb(gb);  // bit_depth_luma_minus8
+        get_ue_golomb(gb);  // bit_depth_chroma_minus8
+        get_bits1(gb);      // qpprime_y_zero_transform_bypass_flag
+
+        if (get_bits1(gb))      // seq_scaling_matrix_present_flag
+        {
+            for (int idx = 0; idx < ((chroma_format_idc != 3) ? 8 : 12); ++idx)
+            {
+                get_bits1(gb);  // scaling_list
+            }
+        }
+    }
+
+    log2_max_frame_num = get_ue_golomb(gb) + 4;
+
+    uint       pic_order_cnt_type;
+    uint       log2_max_pic_order_cnt_lsb;
+    bool       delta_pic_order_always_zero_flag;
+    int        offset_for_non_ref_pic;
+    int        offset_for_top_to_bottom_field;
+    uint       tmp;
+    uint       num_ref_frames;
+    bool       gaps_in_frame_num_allowed_flag;
+    uint       pic_width_in_mbs;
+    uint       pic_height_in_map_units;
+
+    pic_order_cnt_type = get_ue_golomb(gb);
+    if (pic_order_cnt_type == 0)
+        log2_max_pic_order_cnt_lsb = get_ue_golomb(gb) + 4;
+    else if (pic_order_cnt_type == 1)
+    {
+        delta_pic_order_always_zero_flag = get_bits1(gb);
+        offset_for_non_ref_pic = get_se_golomb(gb);
+        offset_for_top_to_bottom_field = get_se_golomb(gb);
+        tmp = get_ue_golomb(gb);
+        for (uint idx = 0; idx < tmp; ++idx)
+            get_se_golomb(gb);  // offset_for_ref_frame[i]
+    }
+
+    num_ref_frames = get_ue_golomb(gb);
+    gaps_in_frame_num_allowed_flag = get_bits1(gb);
+    pic_width_in_mbs = get_ue_golomb(gb) + 1;
+    pic_height_in_map_units = get_ue_golomb(gb) + 1;
+    frame_mbs_only_flag = get_bits1(gb);
+
+}
+
+
 } // namespace H264

libs/libmythtv/mpeg/h264utils.h

@@ -35 +35 @@
 
 #include <stdint.h>
 
+extern "C" {
+#include "golomb.h"
+}
+
 namespace H264
 {
 
@@ -174 +178 @@
 
   private:
     void KeyframePredicate(const uint8_t new_first_NAL_byte); /* throw() */
+    void decode_Header(GetBitContext * gb);
+    void decode_SPS(GetBitContext * gb);
 
     bool    errored;
     bool    state_changed;
@@ -182 +188 @@
     int64_t  sync_stream_offset;
 
     uint8_t first_NAL_byte;
+    int     log2_max_frame_num;
+    int     frame_num, prev_frame_num;
 
     bool    saw_AU_delimiter;
     bool    saw_first_VCL_NAL_unit;
     bool    saw_sps;
+    bool    new_VLC_NAL;
+
+    bool    separate_colour_plane_flag;
+    bool    frame_mbs_only_flag;
+    bool    prev_field_pic_flag;
+    bool    prev_bottom_field_flag;
+    uint    prev_pic_parameter_set_id;
+
 
     bool    did_evaluate_once;
     bool    keyframe;
     int64_t keyframe_sync_stream_offset;
+
+    GetBitContext gb;
 };
 
 } // namespace H264