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• How to compile c99-to-c89 convertor with clang ?

  27 septembre 2016, par theateist

  I’m trying to compile ffmpeg in windows for VisualStudio and one of the step is to compile c99-to-c89 code with clang according to this post. I managed to create clang.exe but how I compile c99-to-c89 code with it ?

  I changed a little bit the makefile in c99-to-c89 so CC variable points now to clang.exe compiler and not cl.exe

  EXT=.exe
  
  
  
  all: c99conv$(EXT) c99wrap$(EXT)
  
  
  
  CLANGDIR=C:/build
  
  CC=C:/build/bin/Release/clang.exe
  
  CFLAGS=-nologo -Z7 -D_CRT_SECURE_NO_WARNINGS=1 -Dpopen=_popen -Dunlink=_unlink -Dstrdup=_strdup -Dsnprintf=_snprintf -I. -I$(CLANGDIR)/tools/clang/include
  
  LDFLAGS=-nologo -Z7 $(CLANGDIR)/lib/Release/libclang.lib
  
  
  
  clean:
  
      rm -f c99conv$(EXT) c99wrap$(EXT) convert.o compilewrap.o
  
      rm -f unit.c.c unit2.c.c
  
  
  
  test1: c99conv$(EXT)
  
      $(CC) -P unit.c -Fiunit.prev.c
  
      ./c99conv unit.prev.c unit.post.c
  
      diff -u unit.{prev,post}.c
  
  
  
  test2: c99conv$(EXT)
  
      $(CC) -P unit2.c -Fiunit2.prev.c
  
      ./c99conv unit2.prev.c unit2.post.c
  
      diff -u unit2.{prev,post}.c
  
  
  
  test3: c99conv$(EXT)
  
      $(CC) $(CFLAGS) -P -Ficonvert.prev.c convert.c
  
      ./c99conv convert.prev.c convert.post.c
  
      diff -u convert.{prev,post}.c
  
  
  
  c99conv$(EXT): convert.o
  
      $(CC) -Fe$@ $< $(LDFLAGS) $(LIBS)
  
  
  
  c99wrap$(EXT): compilewrap.o
  
      $(CC) -Fe$@ $< $(LDFLAGS)
  
  
  
  %.o: %.c
  
      $(CC) $(CFLAGS) -Fo$@ -c $<

  but when I run make command I get clang: error: unsupported use of internal gcc -Z option '-Z7'. I guess the problem in CFLAGS and LDFLAGS but I don’t know how to fix it because the lack of knowledge in makefile and clang.

• ffmpeg unexpected exit code 1 for -list_devices and -list_options

  8 janvier 2024, par djvg

  Description

  


  If I run any of the following commands from the examples in the documentation, using ffmpeg 4.2.2 on Windows 10, the requested information is successfully displayed in the console, but the process exits with exit code 1, instead of the expected 0 (success).

  


  ffmpeg -list_devices true -f dshow -i dummy

ffmpeg -list_options true -f dshow -i video="MyCamera"


  


  As far as I know, exit code 1 on Windows implies "Incorrect function", so I consider this behavior to be unexpected.

  


  If I stream camera input to disk, using e.g. ffmpeg -f dshow -i video="MyCamera" "myfile.mp4", then stop using q, the exit code is 0, as expected.

  


  Question

  


  Does the exit code 1 constitute normal behavior for ffmpeg, or am I doing something wrong ?

  


  Relevance

  


  When running the commands manually, from the command line, the exit code does not make much difference, as long as the requested information is displayed.

  


  However, when running the commands programmatically, it may cause trouble. For example, using Python's subprocess.run(..., check=True), the nonzero exit code causes a CalledProcessError.

  


  Of course there are ways around this, e.g. use check=False, but the point is that a workaround would not be necessary if ffmpeg behaved as expected, i.e. returned 0.

  


• recording live stream video from tv card using ffmpeg at window [on hold]

  6 décembre 2013, par user2688423

  I want to record live stream every 1 second from tv card(tv signal) using ffmpeg in window.

  first of all, to record live video from tv card, I tried below.

  1. First I tried this.

  ffmpeg -list_devices true -f dshow -i dummy

  then the result is

  " [dshow @ 000000000024e6fe0] DirectShow video devices
  [dshow @000000000024e6fe0] "SKYTV HD USB Maxx Video Capture"
  [dshow @
  000000000024e6fe0] DirectShow audio devices
  [dshow @
  000000000024e6fe0] "Analog Audio In(SKYTV HD USB Ma" "

  so I tried

  ffmpeg -f dshow -i video="SKYTV HD USB Maxx Video Capture" -r 20
  -threads 0 D ://test.mkv

  But it didn't work. the Error message is

  "[dshow@000000000034d920] Could not run filter
  video=SKYTV HD USB
  Maxx Video Capture : Input/output error"

  I use the device called 'SKYTV HD USB Maxx Video Capture' for getting tv signal(TV card).

  1. The First way deosn't work, I tried different way.

  ffmpeg -y -f vfwcap -i list

  then the result is
  "

  [dshow @ 00000000003fd760] Driver 0

  [dshow @ 00000000003fd760] Microsoft WDM Image Capture (Win32)
  [dshow @ 00000000003fd760] Version : 6.1.7601.17514 list : Input/output error

  "

  so I tried

  ffmpeg -y -f vfwcap -r 25 -i 0 D ://out.mp4

  then, there is some out.mp4 file in D drive but the file is nothing.
  (I think it is not TV signal)

  what should i do to record live video every 1 second from tv card(tv signal) using ffmpeg in window ? And How can I set channel at tvcard(Because I want to get tv signal, there are many channels).

  Please help..!