diff --git a/src/file_m2ts.c b/src/file_m2ts.c
index 2c083ded..99d1b235 100644
--- a/src/file_m2ts.c
+++ b/src/file_m2ts.c
@@ -31,9 +31,9 @@
 #include "types.h"
 #include "filegen.h"
 
-/*@ requires \valid(file_stat); */
+/*@ requires valid_register_header_check(file_stat); */
 static void register_header_check_m2ts(file_stat_t *file_stat);
-/*@ requires \valid(file_stat); */
+/*@ requires valid_register_header_check(file_stat); */
 static void register_header_check_ts(file_stat_t *file_stat);
 
 const file_hint_t file_hint_m2ts= {
@@ -60,14 +60,9 @@ static const unsigned char tshv_header[4] = { 'T','S','H','V'};
 static const unsigned char sdvs_header[4] = { 'S','D','V','S'};
 
 /*@
-  @ requires buffer_size > 0;
-  @ requires (buffer_size&1)==0;
-  @ requires \valid_read(buffer+(0..buffer_size-1));
-  @ requires \valid(file_recovery);
   @ requires file_recovery->data_check==&data_check_ts_192;
-  @ requires file_recovery->calculated_file_size <= PHOTOREC_MAX_FILE_SIZE;
-  @ requires \separated(buffer + (..), file_recovery);
-  @ ensures \result == DC_CONTINUE || \result == DC_STOP;
+  @ requires valid_data_check_param(buffer, buffer_size, file_recovery);
+  @ ensures  valid_data_check_result(\result, file_recovery);
   @ assigns file_recovery->calculated_file_size;
   @*/
 static data_check_t data_check_ts_192(const unsigned char *buffer, const unsigned int buffer_size, file_recovery_t *file_recovery)
@@ -86,8 +81,9 @@ static data_check_t data_check_ts_192(const unsigned char *buffer, const unsigne
 }
 
 /*@
-  @ requires \valid(file_recovery);
-  @ requires valid_file_recovery(file_recovery);
+  @ requires file_recovery->file_rename==&file_rename_ts_188;
+  @ requires valid_file_rename_param(file_recovery);
+  @ ensures  valid_file_rename_result(file_recovery);
   @*/
 static void file_rename_ts_188(file_recovery_t *file_recovery)
 {
@@ -116,8 +112,9 @@ static void file_rename_ts_188(file_recovery_t *file_recovery)
 }
 
 /*@
-  @ requires \valid(file_recovery);
-  @ requires valid_file_recovery(file_recovery);
+  @ requires file_recovery->file_rename==&file_rename_ts_192;
+  @ requires valid_file_rename_param(file_recovery);
+  @ ensures  valid_file_rename_result(file_recovery);
   @*/
 static void file_rename_ts_192(file_recovery_t *file_recovery)
 {
@@ -146,14 +143,10 @@ static void file_rename_ts_192(file_recovery_t *file_recovery)
 }
 
 /*@
-  @ requires buffer_size > 0;
-  @ requires \valid_read(buffer+(0..buffer_size-1));
-  @ requires valid_file_recovery(file_recovery);
-  @ requires \valid(file_recovery_new);
-  @ requires file_recovery_new->blocksize > 0;
+  @ requires buffer_size >= 0xe8 + 4;
   @ requires separation: \separated(&file_hint_m2ts, &file_hint_ts, buffer+(..), file_recovery, file_recovery_new);
-  @ ensures \result == 0 || \result == 1;
-  @ ensures  \result!=0 ==> valid_file_recovery(file_recovery_new);
+  @ requires valid_header_check_param(buffer, buffer_size, safe_header_only, file_recovery, file_recovery_new);
+  @ ensures  valid_header_check_result(\result, file_recovery_new);
   @*/
 static int header_check_m2ts(const unsigned char *buffer, const unsigned int buffer_size, const unsigned int safe_header_only, const file_recovery_t *file_recovery, file_recovery_t *file_recovery_new)
 {
@@ -202,14 +195,9 @@ static int header_check_m2ts(const unsigned char *buffer, const unsigned int buf
 }
 
 /*@
-  @ requires buffer_size > 0;
-  @ requires (buffer_size&1)==0;
-  @ requires \valid_read(buffer+(0..buffer_size-1));
-  @ requires \valid(file_recovery);
   @ requires file_recovery->data_check==&data_check_ts_188;
-  @ requires file_recovery->calculated_file_size <= PHOTOREC_MAX_FILE_SIZE;
-  @ requires \separated(buffer + (..), file_recovery);
-  @ ensures \result == DC_CONTINUE || \result == DC_STOP;
+  @ requires valid_data_check_param(buffer, buffer_size, file_recovery);
+  @ ensures  valid_data_check_result(\result, file_recovery);
   @ assigns file_recovery->calculated_file_size;
   @*/
 static data_check_t data_check_ts_188(const unsigned char *buffer, const unsigned int buffer_size, file_recovery_t *file_recovery)
@@ -228,14 +216,10 @@ static data_check_t data_check_ts_188(const unsigned char *buffer, const unsigne
 }
 
 /*@
-  @ requires buffer_size > 0;
-  @ requires \valid_read(buffer+(0..buffer_size-1));
-  @ requires valid_file_recovery(file_recovery);
-  @ requires \valid(file_recovery_new);
-  @ requires file_recovery_new->blocksize > 0;
+  @ requires buffer_size >= 0x18b+sizeof(tshv_header);
   @ requires separation: \separated(&file_hint_m2ts, &file_hint_ts, buffer+(..), file_recovery, file_recovery_new);
-  @ ensures \result == 0 || \result == 1;
-  @ ensures  \result!=0 ==> valid_file_recovery(file_recovery_new);
+  @ requires valid_header_check_param(buffer, buffer_size, safe_header_only, file_recovery, file_recovery_new);
+  @ ensures  valid_header_check_result(\result, file_recovery_new);
   @ assigns  *file_recovery_new;
   @*/
 static int header_check_m2t(const unsigned char *buffer, const unsigned int buffer_size, const unsigned int safe_header_only, const file_recovery_t *file_recovery, file_recovery_t *file_recovery_new)