Improve the tsplay help for "-help ps" to explain what the PID values

are actually used for, and why (before it was definitely confusing).

--HG--
extra : convert_revision : svn%3Aeff31bef-be4a-0410-a8fe-e47997df2690/trunk%40133

tsplay.c

@@ -986,7 +986,7 @@ static void print_help_ps()
     "                    This switch has no effect on MPEG-1 PS data.\n"
     "  -notdvd, -nodvd   The PS data is not from a DVD.\n"
     "\n"
-    "Specifying audio/video streams:\n"
+    "Specifying which audio/video streams to read:\n"
     "\n"
     "  -vstream <n>      Take video from video stream <n> (0..7).\n"
     "                    The default is the first video stream found.\n"
@@ -999,15 +999,19 @@ static void print_help_ps()
     "                    is assumed to have determined which one is wanted,\n"
     "                    e.g., using psreport)\n"
     "\n"
-    "  -vpid <pid>       <pid> is the video PID to use for the data.\n"
+    "The input PS data does not have PAT/PMT or PID values, and thus tsplay\n"
+    "must invent them. The following switches may be used to choose particular\n"
+    "PID values:\n"
+    "\n"
+    "  -vpid <pid>       <pid> is the PID to output video data with.\n"
     "                    Use '-vpid 0x<pid>' to specify a hex value.\n"
     "                    Defaults to 0x68.\n"
-    "  -apid <pid>       <pid> is the audio PID to use for the data.\n"
+    "  -apid <pid>       <pid> is the PID to output audio data with.\n"
     "                    Use '-apid 0x<pid>' to specify a hex value.\n"
     "                    Defaults to 0x67.\n"
-    "  -pmt <pid>        <pid> is the PMT PID to use.\n"
+    "  -pmt <pid>        <pid> is the PID to output PMT data with.\n"
     "                    Use '-pmt 0x<pid>' to specify a hex value.\n"
-    "                    Defaults to 0x66\n"
+    "                    Defaults to 0x66.\n"
     "\n"
     "The default values for the various PIDs should suffice in most cases\n"
     "\n"
@@ -1018,6 +1022,9 @@ static void print_help_ps()
     "  -dolby dvb       Use stream type 0x06 (the default)\n"
     "  -dolby atsc      Use stream type 0x81\n"
     "\n"
+    "Finally, it is occasionally useful to tweak how often PAT/PMT are written,\n"
+    "and how much padding the stream starts with:\n"
+    "\n"
     "  -prepeat <n>      Output the program data (PAT/PMT) after every <n>\n"
     "                    PS packs, to allow a TS reader to resynchronise\n"
     "                    if it starts reading part way through the stream.\n"