Remove unused bytes from uncompressed header.

Although they are called "sync codes", nothing is synchronized
using them.

Change-Id: I2dbd67daf9f4822438323212bb96cac489c38c5d

av1/av1_dx_iface.c

@@ -290,8 +290,6 @@ static aom_codec_err_t decoder_peek_si_internal(
     }
 #endif
     if (si->is_kf) {
-      if (!av1_read_sync_code(&rb)) return AOM_CODEC_UNSUP_BITSTREAM;
-
       if (!parse_bitdepth_colorspace_sampling(profile, &rb))
         return AOM_CODEC_UNSUP_BITSTREAM;
       av1_read_frame_size(&rb, (int *)&si->w, (int *)&si->h);
@@ -301,7 +299,6 @@ static aom_codec_err_t decoder_peek_si_internal(
       rb.bit_offset += error_resilient ? 0 : 2;  // reset_frame_context
 
       if (intra_only_flag) {
-        if (!av1_read_sync_code(&rb)) return AOM_CODEC_UNSUP_BITSTREAM;
         if (profile > PROFILE_0) {
           if (!parse_bitdepth_colorspace_sampling(profile, &rb))
             return AOM_CODEC_UNSUP_BITSTREAM;

av1/common/common.h

@@ -50,10 +50,6 @@ static INLINE int get_unsigned_bits(unsigned int num_values) {
 
 #define CHECK_MEM_ERROR(cm, lval, expr) \
   AOM_CHECK_MEM_ERROR(&cm->error, lval, expr)
-// TODO(yaowu: validate the usage of these codes or develop new ones.)
-#define AV1_SYNC_CODE_0 0x49
-#define AV1_SYNC_CODE_1 0x83
-#define AV1_SYNC_CODE_2 0x43
 
 #define AOM_FRAME_MARKER 0x2
 

av1/decoder/decodeframe.c

@@ -4722,9 +4722,6 @@ static size_t read_uncompressed_header(AV1Decoder *pbi,
   }
 #endif
   if (cm->frame_type == KEY_FRAME) {
-    if (!av1_read_sync_code(rb))
-      aom_internal_error(&cm->error, AOM_CODEC_UNSUP_BITSTREAM,
-                         "Invalid frame sync code");
 #if !CONFIG_OBU
     read_bitdepth_colorspace_sampling(cm, rb, pbi->allow_lowbitdepth);
 #endif
@@ -4795,9 +4792,6 @@ static size_t read_uncompressed_header(AV1Decoder *pbi,
 #endif
 
     if (cm->intra_only) {
-      if (!av1_read_sync_code(rb))
-        aom_internal_error(&cm->error, AOM_CODEC_UNSUP_BITSTREAM,
-                           "Invalid frame sync code");
 #if !CONFIG_OBU
       read_bitdepth_colorspace_sampling(cm, rb, pbi->allow_lowbitdepth);
 #endif
@@ -5352,12 +5346,6 @@ static struct aom_read_bit_buffer *init_read_bit_buffer(
 
 //------------------------------------------------------------------------------
 
-int av1_read_sync_code(struct aom_read_bit_buffer *const rb) {
-  return aom_rb_read_literal(rb, 8) == AV1_SYNC_CODE_0 &&
-         aom_rb_read_literal(rb, 8) == AV1_SYNC_CODE_1 &&
-         aom_rb_read_literal(rb, 8) == AV1_SYNC_CODE_2;
-}
-
 void av1_read_frame_size(struct aom_read_bit_buffer *rb, int *width,
                          int *height) {
   *width = aom_rb_read_literal(rb, 16) + 1;

av1/decoder/decodeframe.h

@@ -24,7 +24,6 @@ struct aom_read_bit_buffer;
 void read_sequence_header(SequenceHeader *seq_params);
 #endif
 
-int av1_read_sync_code(struct aom_read_bit_buffer *const rb);
 void av1_read_frame_size(struct aom_read_bit_buffer *rb, int *width,
                          int *height);
 BITSTREAM_PROFILE av1_read_profile(struct aom_read_bit_buffer *rb);

av1/encoder/bitstream.c

@@ -4268,12 +4268,6 @@ static void write_frame_size_with_refs(AV1_COMP *cpi,
   if (!found) write_frame_size(cm, wb);
 }
 
-static void write_sync_code(struct aom_write_bit_buffer *wb) {
-  aom_wb_write_literal(wb, AV1_SYNC_CODE_0, 8);
-  aom_wb_write_literal(wb, AV1_SYNC_CODE_1, 8);
-  aom_wb_write_literal(wb, AV1_SYNC_CODE_2, 8);
-}
-
 static void write_profile(BITSTREAM_PROFILE profile,
                           struct aom_write_bit_buffer *wb) {
   switch (profile) {
@@ -4566,7 +4560,6 @@ static void write_uncompressed_header_frame(AV1_COMP *cpi,
 #endif
 
   if (cm->frame_type == KEY_FRAME) {
-    write_sync_code(wb);
     write_bitdepth_colorspace_sampling(cm, wb);
     write_frame_size(cm, wb);
     write_sb_size(cm, wb);
@@ -4609,7 +4602,6 @@ static void write_uncompressed_header_frame(AV1_COMP *cpi,
 #endif  // CONFIG_EXT_REFS
 
     if (cm->intra_only) {
-      write_sync_code(wb);
       write_bitdepth_colorspace_sampling(cm, wb);
 
 #if CONFIG_EXT_REFS
@@ -4852,7 +4844,6 @@ static void write_uncompressed_header_obu(AV1_COMP *cpi,
 #endif
 
   if (cm->frame_type == KEY_FRAME) {
-    write_sync_code(wb);
     write_frame_size(cm, wb);
     write_sb_size(cm, wb);
 
@@ -4887,8 +4878,6 @@ static void write_uncompressed_header_obu(AV1_COMP *cpi,
 #endif  // CONFIG_EXT_REFS
 
     if (cm->intra_only) {
-      write_sync_code(wb);
-
 #if CONFIG_EXT_REFS
       aom_wb_write_literal(wb, cpi->refresh_frame_mask, REF_FRAMES);
 #else