simple real-time logging ffmpeg with Tprocess - example
lazarus / 21-General

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john60 · 2023-05-23 15:48

Maybe this will help someone - just my take on it:
using lazarus 2.2.0 - FPC 3.2.2   Standard Tprocess

I have this integrated into my toolkit and it runs fine there
Even using the Line filterFFMPEGoutput(outStr) which does some
filtering on
the log output before display into synEdit - speed is no different to
running
in a dos batch file and no windoze locking up (hints and buttons etc) 
all work fine.

Using Nvenc I get 10x speed when re-compressing video
Using x264 about 2.4x
Setting Tprocess to realtime or high makes no difference -
I expect ffmpeg is running at lower speed than my system or whatever.
The abort stuff can be ignored as can the filer line (Just send
'output' to your destination there.)
I didn't get on well with TAsyncProcess - and didn't see the need for
memory streams etc as in
other examples but perhaps this makes it cleared what those are
actually doing in the background.
Anyway - enjoy.

Code: Pascal  [Select][+][-]window.onload = function(){var x1 =
document.getElementById("main_content_section"); if (x1) { var x =
document.getElementsByClassName("geshi");for (var i = 0; i // OutStr
and myStr are TString// For TProcess options I haveproc.Options := [
poUsePipes,poStdErrToOutPut,poNoConsole,poRunIdle ]; // BUF_SIZE =
2048 - The loop seldom exceeds 1024 bytes if ever.(May be
system/application dependent)proc.Execute;WHILE proc.Running
doBEGIN//abortstuff     application.ProcessMessages;     if userAbort
= true then processAbort(locData);              // include some debug
info if aborting//end abortstuff//Read current pipe data into buffer
and process it     BytesRead :=
proc.Output.Read(buffer,proc.Output.NumBytesAvailable); //Get process
output byte count data into the buffer     if BytesRead >0  then     
                                         //or nothing to do     BEGIN 
     for k := 1 to BytesRead do                       // Read the
buffer 1 byte at a time         begin              myStr := myStr +
chr(buffer[k]);          // just add to the string - if a partial
string was already in it - it will be completed              if
chr(Buffer[k]) = #13 then              // Using this line to judge EOL
for my current OS (windoze)              begin                outStr
:= '';                for j := 1 to length(myStr) do                 
// The j loop simply chops out extra #10#13 outherwise output is
double spaced                  if (myStr[j] = #10) or (myStr[j] = #13)
then   // could be done a shade quicker but this keeps things clearer
maybe                     continue                                  
 // especially since #13#10 could be split across the partial string
boundry for myStr                  else                      outStr :=
outStr + myStr[j];                filterFFMPEGoutput(outStr);        
     //if a full line - output it - or if filtered etc. do that      
        myStr := '';                              // ... if full line
completed clear the string otherwise the partial line is ...         
   end;//#13                                   // ... left for
completion next "while proc.running" loop.             
application.ProcessMessages;         end;//k     END;//>0END;//WHILE
runningfrmJs.synEDdataFFMPEG.Lines.Add(#10#13 + '*** END OF FILE ***'
+ #10#13#10#13 ); // just a notice for logging clarity
john