ReadProgramData() Working Properly?

chris319 · **Joined:** Mon Oct 24, 2005 1:05 pm **Posts:** 693

I'm not sure ReadProgramData() is working properly under Linux. It keeps returning 0. Under Windows 10 it returns a non-zero number.

RunProgram() is being used to set up the pipe and readFrame is the result, which is non zero.

Code:

count = ReadProgramData(readFrame, @frame(0), #H * #W * 3)

It works under Windows 10.

NicTheQuick · **Posted:** Wed Dec 05, 2018 11:45 am

It's working for me.

Code:

*buf = AllocateMemory(1024 * 1024)

prog.i = RunProgram("/usr/bin/w", "", "", #PB_Program_Read | #PB_Program_UTF8 | #PB_Program_Open)

count.i = ReadProgramData(prog, *buf, 1024 * 1024)

Debug count

result.s = PeekS(*buf, -1, #PB_UTF8)

Debug result

CloseProgram(prog)

chris319 · **Joined:** Mon Oct 24, 2005 1:05 pm **Posts:** 693

You're using it to read UTF8 text. Try reading some data with ffmpeg from an mp4 file.

NicTheQuick · **Posted:** Wed Dec 05, 2018 3:15 pm

This works also. I am using random data instead of a video file. That should not make any difference. Of course the PeekS() returns nonsense this way.

Code:

*buf = AllocateMemory(1024 * 1024)

prog.i = RunProgram("/bin/cat", "/dev/urandom", "", #PB_Program_Read | #PB_Program_Open)

count.i = ReadProgramData(prog, *buf, 1024 * 1024)

Debug count

result.s = PeekS(*buf, -1, #PB_Ascii)

Debug result

CloseProgram(prog)

chris319 · **Joined:** Mon Oct 24, 2005 1:05 pm **Posts:** 693

The pipe opens successfully in Linux.

ReadProgramData() keeps returning 0.

It works in Windows.

Code:

pipeIn$ = "-i " + filename$ + " -f image2pipe  -s 1280x720  -pix_fmt rgb24  -r 59.94  -vf zscale=in_range=limited:out_range=limited  -vcodec rawvideo -"

;readFrame = RunProgram("/usr/bin/ffmpeg", pipeIn$,"/home/chris/PureBasic/source/",#PB_Program_Open | #PB_Program_Read)
readFrame = RunProgram("ffmpeg", pipeIn$,"",#PB_Program_Open | #PB_Program_Read)
If readFrame = 0
  MessageRequester("Error", "unable to open pipe")
  End
Else
  MessageRequester("Success","Pipe opened")
EndIf

For ct = 1 To 30 ;READ FIRST 30 FRAMES
 
count = ReadProgramData(readFrame, @frame(0), #H * #W * 3)
Debug count
Next

NicTheQuick · **Posted:** Wed Dec 05, 2018 7:29 pm

Maybe you have to wait until ffmpeg is returning the result. ReadProgramData() does not wait until the given buffer is full. You may have to read data until ProgramRunning() returns #False. Then you've got all the data you are looking for.
Maybe so:

Code:

pipeIn$ = "-i " + filename$ + " -f image2pipe  -s 1280x720  -pix_fmt rgb24  -r 59.94  -vf zscale=in_range=limited:out_range=limited  -vcodec rawvideo -"

;readFrame = RunProgram("/usr/bin/ffmpeg", pipeIn$,"/home/chris/PureBasic/source/",#PB_Program_Open | #PB_Program_Read)
readFrame = RunProgram("ffmpeg", pipeIn$,"",#PB_Program_Open | #PB_Program_Read)
If readFrame = 0
   MessageRequester("Error", "unable to open pipe")
   End
Else
   MessageRequester("Success","Pipe opened")
EndIf

bytesReadSum.i = 0
bytesRead.i = 0
While ProgramRunning(readFrame)
   bytesRead = ReadProgramData(readFrame, @frame(0), #H * #W * 3)
   If bytesRead :
      bytesReadSum + bytesRead
      Debug bytesReadSum
   EndIf
Next

But of course this will not work together with your frame array. You have to change more than I did.

chris319 · **Joined:** Mon Oct 24, 2005 1:05 pm **Posts:** 693

Using AvailableProgramOutput() causes the program to wait forever for data which never arrives.

The program has to keep running to process subsequent frames.

This works in Windows and it works in Linux using the C language, so I have to conclude there is a problem with PB in Linux.

chris319 · **Joined:** Mon Oct 24, 2005 1:05 pm **Posts:** 693

ReadProgramData() works OK on my big computer at home.

Here I sit in a hotel room using a tablet computer. Both machines are running Wndows 10. The tablet computer seems to have problems setting up pipes; the big computer does not.

Go figure.

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ReadProgramData() Working Properly?

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