Broken pipe when writing to external program's stream

[Martin Buchmann]

Maybe this is related to bug # 1405921 but I see a dependency on the OS version which is not reported there. I want to write data to an external instance of ffmpeg to create some videos for visualization. While the code is working on a Linux setup of the original author and on macOS 10.13. it fails on macOS 10.15. with the following error:

Couldn't write to #<SB-SYS:FD-STREAM for "descriptor 7" {100227EB23}>:
  Broken pipe

I made sure that SBCL is allowed to access the hard drive and control other programs in macOS' security settings. Everything works for a simple example as given in Edi Weitz' book (http://weitz.de/cl-recipes/, page 688) but not for the code below.

Please let me know if I can provide anymore information.

This is how far I could boil it down:

-- minimal.lisp

;; Using external-program
(ql:quickload "external-program")

;; The size of the video
(defparameter *width* 640)
(defparameter *height* 480)

;; Setting up ffmpeg
(defparameter *ffmpeg-args*
  (list "-loglevel" "debug"
        "-nostats"
        "-nostdin"
        "-f" "rawvideo"
        "-s" (format nil "~Dx~D" *width* *height*)
        "-pix_fmt" "bgra"
        "-r" (format nil "~D" 25)
        "-i" "-"
        "-an"
        "-f" "mp4"
        "-pix_fmt" "yuv420p"
        "-c:v" "libx264"
        "-profile:v" "main"
        "-level" "3.1"
        "-y"
        "out.mp4"))

;; Make sure ffmpeg is installed and found in $PATH
(defparameter *p*
  (external-program:start "ffmpeg" *ffmpeg-args*
                          :input :stream :output t :error :output))
;; I get a running process after this line

(let ((buffer (make-array (* *width* *height* 4)
                          :element-type '(unsigned-byte 8) :initial-element 255)
              ;; 0 means a complete black frame
              ;; 255 means a complete white frame
              ))

  (dotimes (i 50)
    (write-sequence buffer (external-program:process-input-stream *p*))
    (format t ";;; Frame: ~,20D~%" i)))

(close (external-program:process-input-stream *p*))

-- SBCL's version

$ sbcl --version
SBCL 1.5.9

-- OS

$ uname -a
Darwin Martins-MBP.fritz.box 19.2.0 Darwin Kernel Version 19.2.0: Sat Nov 9 03:47:04 PST 2019; root:xnu-6153.61.1~20/RELEASE_X86_64 x86_64

--

*features*

(:OSICAT-FD-STREAMS CFFI-FEATURES:FLAT-NAMESPACE CFFI-FEATURES:X86-64
 CFFI-FEATURES:UNIX CFFI-FEATURES:DARWIN :CFFI CFFI-SYS::FLAT-NAMESPACE
 ALEXANDRIA.1.0.0::SEQUENCE-EMPTYP :QUICKLISP :SB-BSD-SOCKETS-ADDRINFO :ASDF3.3
 :ASDF3.2 :ASDF3.1 :ASDF3 :ASDF2 :ASDF :OS-MACOSX :OS-UNIX
 :NON-BASE-CHARS-EXIST-P :ASDF-UNICODE :X86-64 :64-BIT :ALIEN-CALLBACKS
 :ANSI-CL :AVX2 :BSD :C-STACK-IS-CONTROL-STACK :CALL-SYMBOL :COMMON-LISP
 :COMPACT-INSTANCE-HEADER :COMPARE-AND-SWAP-VOPS :CYCLE-COUNTER :DARWIN
 :FP-AND-PC-STANDARD-SAVE :GENCGC :IEEE-FLOATING-POINT :IMMOBILE-CODE
 :IMMOBILE-SPACE :INODE64 :INTEGER-EQL-VOP :LINKAGE-TABLE :LITTLE-ENDIAN
 :MACH-EXCEPTION-HANDLER :MACH-O :OS-PROVIDES-BLKSIZE-T :OS-PROVIDES-DLADDR
 :OS-PROVIDES-DLOPEN :OS-PROVIDES-PUTWC :OS-PROVIDES-SUSECONDS-T
 :PACKAGE-LOCAL-NICKNAMES :RELOCATABLE-HEAP :SB-CORE-COMPRESSION :SB-DOC
 :SB-EVAL :SB-LDB :SB-PACKAGE-LOCKS :SB-SIMD-PACK :SB-SIMD-PACK-256
 :SB-SOURCE-LOCATIONS :SB-THREAD :SB-UNICODE :SB-XREF-FOR-INTERNALS :SBCL
 :STACK-ALLOCATABLE-CLOSURES :STACK-ALLOCATABLE-FIXED-OBJECTS
 :STACK-ALLOCATABLE-LISTS :STACK-ALLOCATABLE-VECTORS
 :STACK-GROWS-DOWNWARD-NOT-UPWARD :UNDEFINED-FUN-RESTARTS :UNIX
 :UNWIND-TO-FRAME-AND-CALL-VOP)

[Stas Boukarev (stassats)]

Can you redo it without using external-program?

[Martin Buchmann (martin-b77)]

I tried with using sb-ext:run-program directly:

(defparameter *p*
  (sb-ext:run-program "/opt/local/bin/ffmpeg" *ffmpeg-args*
                          :input :stream :output t :error :output :wait nil))

(let ((buffer (make-array (* *width* *height* 4)
                          :element-type '(unsigned-byte 8) :initial-element 255)
              ;; 0 means a complete black frame
              ;; 255 means a complete white frame
              ))

  (dotimes (i 50)
    (write-sequence buffer (sb-ext::process-input *p*))
    (format t ";;; Frame: ~,20D~%" i)))

But get the same error, at least it looks similar to me:

Couldn't write to #<SB-SYS:FD-STREAM for "descriptor 16" {1001C3ED73}>:
  Broken pipe

[Stas Boukarev (stassats)]

And... can't reproduce.

[Martin Buchmann (martin-b77)]

Hmm, I am sorry! I don't know why it is working with macOS 10.13. and not with macOS 10.15. anymore for me. If there is anything I could do to provide more information I would be happy to do so. I was hoping that someone with more insights in the SBCL interna could tell what's going on.

[Stas Boukarev (stassats)]

Are ffmpeg version the same? Maybe the newer ffmpeg doesn't understand your arguments or inputs.

[Martin Buchmann (martin-b77)]

FFmpeg is the same on both machines:

ffmpeg version 4.2.1 Copyright (c) 2000-2019 the FFmpeg developers
  built with Apple clang version 11.0.0 (clang-1100.0.33.8)
  configuration: --prefix=/opt/local --enable-swscale --enable-avfilter --enable-avresample --enable-libmp3lame --enable-libvorbis --enable-libopus --enable-librsvg --enable-libtheora --enable-libopenjpeg --enable-libmodplug --enable-libvpx --enable-libsoxr --enable-libspeex --enable-libass --enable-libbluray --enable-lzma --enable-gnutls --enable-fontconfig --enable-libfreetype --enable-libfribidi --disable-libjack --disable-libopencore-amrnb --disable-libopencore-amrwb --disable-libxcb --disable-libxcb-shm --disable-libxcb-xfixes --disable-indev=jack --enable-opencl --disable-outdev=xv --enable-audiotoolbox --enable-videotoolbox --enable-sdl2 --disable-securetransport --mandir=/opt/local/share/man --enable-shared --enable-pthreads --cc=/usr/bin/clang --arch=x86_64 --enable-x86asm --enable-libx265 --enable-gpl --enable-postproc --enable-libx264 --enable-libxvid
  libavutil 56. 31.100 / 56. 31.100
  libavcodec 58. 54.100 / 58. 54.100
  libavformat 58. 29.100 / 58. 29.100
  libavdevice 58. 8.100 / 58. 8.100
  libavfilter 7. 57.100 / 7. 57.100
  libavresample 4. 0. 0 / 4. 0. 0
  libswscale 5. 5.100 / 5. 5.100
  libswresample 3. 5.100 / 3. 5.100
  libpostproc 55. 5.100 / 55. 5.100
Splitting the commandline.
Reading option '-loglevel' ... matched as option 'loglevel' (set logging level) with argument 'debug'.
Reading option '-nostats' ... matched as option 'stats' (print progress report during encoding) with argument 0.
Reading option '-nostdin' ... matched as option 'stdin' (enable or disable interaction on standard input) with argument 0.
Reading option '-f' ... matched as option 'f' (force format) with argument 'rawvideo'.
Reading option '-s' ... matched as option 's' (set frame size (WxH or abbreviation)) with argument '640x480'.
Reading option '-pix_fmt' ... matched as option 'pix_fmt' (set pixel format) with argument 'bgra'.
Reading option '-r' ... matched as option 'r' (set frame rate (Hz value, fraction or abbreviation)) with argument '25'.
Reading option '-i' ... matched as input url with argument '-'.
Reading option '-an' ... matched as option 'an' (disable audio) with argument '1'.
Reading option '-f' ... matched as option 'f' (force format) with argument 'mp4'.
Reading option '-pix_fmt' ... matched as option 'pix_fmt' (set pixel format) with argument 'yuv420p'.
Reading option '-c:v' ... matched as option 'c' (codec name) with argument 'libx264'.
Reading option '-profile:v' ... matched as option 'profile' (set profile) with argument 'main'.
Reading option '-level' ... matched as AVOption 'level' with argument '3.1'.
Reading option '-y' ... matched as option 'y' (overwrite output files) with argument '1'.
Reading option 'out.mp4' ... matched as output url.
Finished splitting the commandline.
Parsing a group of options: global .
Applying option loglevel (set logging level) with argument debug.
Applying option nostats (print progress report during encoding) with argument 0.
Applying option nostdin (enable or disable interaction on...

[Stas Boukarev (stassats)]

Can you replicate it on CCL?

[Martin Buchmann (martin-b77)]

Hmm, I really think this is more complex than I could handle...

I installed ccl on macOS 10.15.2 but it fails also:

The value 255 is not of the expected type CHARACTER.
   [Condition of type TYPE-ERROR]

Restarts:
 0: [RETRY] Retry SLIME interactive evaluation request.
 1: [*ABORT] Return to SLIME's top level.
 2: [ABORT-BREAK] Reset this thread
 3: [ABORT] Kill this thread

Backtrace:
  0: (CCL::%PRIVATE-IOBLOCK-WRITE-U8-ENCODED-CHAR #S(CCL::IOBLOCK :STREAM #<BASIC-CHARACTER-OUTPUT-STREAM UTF-8 (PIPE/8) #x30200169BA7D> :UNTYI-CHAR NIL :INBUF ...) 255)
      Locals:
        IOBLOCK = #S(CCL::IOBLOCK :STREAM #<BASIC-CHARACTER-OUTPUT-STREAM UTF-8 (PIPE/8) #x30200169BA7D> :UNTYI-CHAR NIL :INBUF ...)
        CHAR = 255
  1: (WRITE-CHAR 1 #<BASIC-CHARACTER-OUTPUT-STREAM UTF-8 (PIPE/8) #x30200169BA7D>)
      Locals:
        CHAR = 1
        CCL:OUTPUT-STREAM = #<BASIC-CHARACTER-OUTPUT-STREAM UTF-8 (PIPE/8) #x30200169BA7D>
        STREAM = #S(CCL::IOBLOCK :STREAM #<BASIC-CHARACTER-OUTPUT-STREAM UTF-8 (PIPE/8) #x30200169BA7D> :UNTYI-CHAR NIL :INBUF ...)
        CCL::IOBLOCK = #S(CCL::IOBLOCK :STREAM #<BASIC-CHARACTER-OUTPUT-STREAM UTF-8 (PIPE/8) #x30200169BA7D> :UNTYI-CHAR NIL :INBUF ...)
  2: (#<CCL::STANDARD-KERNEL-METHOD STREAM-WRITE-VECTOR (CCL::CHARACTER-OUTPUT-STREAM T T T)> #<BASIC-CHARACTER-OUTPUT-STREAM UTF-8 (PIPE/8) #x30200169BA7D> #(255 255 255 255 255 255 ...) 0 1228800)
      Locals:
        STREAM = #<BASIC-CHARACTER-OUTPUT-STREAM UTF-8 (PIPE/8) #x30200169BA7D>
        VECTOR = #(255 255 255 255 255 255 ...)
        START = 0
        END = 1228800
        I = 0
  3: (CCL::%CALL-NEXT-METHOD (NIL #<CCL::STANDARD-KERNEL-METHOD STREAM-WRITE-VECTOR (CCL::CHARACTER-OUTPUT-STREAM T T T)> . 9740067))
      Locals:
        MAGIC = (NIL #<CCL::STANDARD-KERNEL-METHOD STREAM-WRITE-VECTOR (CCL::CHARACTER-OUTPUT-STREAM T T T)> . 9740067)
        ARGS = NIL
        NEXT-METHODS = (#<CCL::STANDARD-KERNEL-METHOD STREAM-WRITE-VECTOR (CCL::CHARACTER-OUTPUT-STREAM T T T)>)
        ARGS = 9740067
        CDR = NIL
        METHOD-FUNCTION = #<METHOD-FUNCTION STREAM-WRITE-VECTOR (CCL::CHARACTER-OUTPUT-STREAM T T T)>
  4: (CCL::%%STANDARD-COMBINED-METHOD-DCODE (#<CCL::STANDARD-KERNEL-METHOD STREAM-WRITE-VECTOR (CCL::BASIC-CHARACTER-OUTPUT-STREAM T T T)> ..) 9740067)
      Locals:
        METHODS = (#<CCL::STANDARD-KERNEL-METHOD STREAM-WRITE-VECTOR (CCL::BASIC-CHARACTER-OUTPUT-STREAM T T T)> #<CCL::STANDARD-KERNEL-METHOD STREAM-WRITE-VECTOR (CCL::CHARACTER-OUTPUT-STREAM T T T)>)
        ARGS = 9740067
        CAR-METHS = #<CCL::STANDARD-KERNEL-METHOD STREAM-WRITE-VECTOR (CCL::BASIC-CHARACTER-OUTPUT-STREAM T T T)>
        CELL-2 = (#<CCL::STANDARD-KERNEL-METHOD STREAM-WRITE-VECTOR (CCL::CHARACTER-OUTPUT-STREAM T T T)> . 9740067)
        MAGIC = (NIL #<CCL::STANDARD-KERNEL-METHOD STREAM-WRITE-VECTOR (CCL::CHARACTER-OUTPUT-STREAM T T T)> . 9740067)
        #:G135334 = #<METHOD-FUNCTION STREAM-WRITE-VECTOR (CCL::BASIC-CHARACTER-OUTPUT-STREAM T T T)>
  5: (NIL #<Unknown Arguments>)
      [No Locals]
  6: (WRITE-SEQUENCE #(255 255 255 255 255 255 ...) #<BASIC-CHARACTER-OUTPUT-STREAM UTF-8 (PIPE/8) #x30200169BA7D> :START 0 :END 1228800)

Because it is expecting a c...

[Martin Buchmann (martin-b77)]

Although, I do not understand it completely if I use CCL and try to close the process-input-stream I get the following error:

Stream #<BASIC-CHARACTER-OUTPUT-STREAM UTF-8 (PIPE/15) #x302001B116AD> is private to #<PROCESS repl-thread(13) [semaphore wait] #x30200113903D>
   [Condition of type SIMPLE-ERROR]

Restarts:
 0: [RETRY] Retry SLIME interactive evaluation request.
 1: [*ABORT] Return to SLIME's top level.
 2: [ABORT-BREAK] Reset this thread
 3: [ABORT] Kill this thread

Backtrace:
  0: (#<CCL::STANDARD-KERNEL-METHOD STREAM-FORCE-OUTPUT (CCL::BASIC-OUTPUT-STREAM)> #<BASIC-CHARACTER-OUTPUT-STREAM UTF-8 (PIPE/15) #x302001B116AD>)
      Locals:
        STREAM = #<BASIC-CHARACTER-OUTPUT-STREAM UTF-8 (PIPE/15) #x302001B116AD>
        IOBLOCK = #S(CCL::IOBLOCK :STREAM #<BASIC-CHARACTER-OUTPUT-STREAM UTF-8 (PIPE/15) #x302001B116AD> :UNTYI-CHAR NIL :INBUF ...)
        #:G152758 = NIL
        OWNER = #<PROCESS repl-thread(13) [semaphore wait] #x30200113903D>
  1: (CCL::%%BEFORE-AND-AFTER-COMBINED-METHOD-DCODE (NIL #<CCL::STANDARD-KERNEL-METHOD CLOSE :BEFORE (CCL::BASIC-OUTPUT-STREAM)> . 9740068))
      Locals:
        MAGIC = (NIL #<CCL::STANDARD-KERNEL-METHOD CLOSE :BEFORE (CCL::BASIC-OUTPUT-STREAM)> . 9740068)
        METHODS = ((#<CCL::STANDARD-KERNEL-METHOD CLOSE :BEFORE (CCL::BASIC-OUTPUT-STREAM)>) (#<CCL::STANDARD-KERNEL-METHOD CLOSE :AFTER (CCL::BASIC-STREAM)>) #<CCL::STANDARD-KERNEL-METHOD CLOSE (STREAM)>)
        BEFORES = (#<CCL::STANDARD-KERNEL-METHOD CLOSE :BEFORE (CCL::BASIC-OUTPUT-STREAM)>)
        CDR-METHS = ((#<CCL::STANDARD-KERNEL-METHOD CLOSE :AFTER (CCL::BASIC-STREAM)>) #<CCL::STANDARD-KERNEL-METHOD CLOSE (STREAM)>)
        PRIMARIES = (#<CCL::STANDARD-KERNEL-METHOD CLOSE (STREAM)>)
        AFTERS = (#<CCL::STANDARD-KERNEL-METHOD CLOSE :AFTER (CCL::BASIC-STREAM)>)
        ARGS = 9740068
        #:G135365 = (#<CCL::STANDARD-KERNEL-METHOD CLOSE :BEFORE (CCL::BASIC-OUTPUT-STREAM)>)
        METHOD = #<CCL::STANDARD-KERNEL-METHOD CLOSE :BEFORE (CCL::BASIC-OUTPUT-STREAM)>
        #:G135369 = #<METHOD-FUNCTION CLOSE :BEFORE (CCL::BASIC-OUTPUT-STREAM)>
  2: (CCL::%%STANDARD-COMBINED-METHOD-DCODE ((#<CCL::STANDARD-KERNEL-METHOD CLOSE :BEFORE (CCL::BASIC-OUTPUT-STREAM)>) (#<CCL::STANDARD-KERNEL-METHOD CLOSE :AFTER (CCL::BASIC-STREAM)>) ..) 9740068)
      Locals:
        METHODS = ((#<CCL::STANDARD-KERNEL-METHOD CLOSE :BEFORE (CCL::BASIC-OUTPUT-STREAM)>) (#<CCL::STANDARD-KERNEL-METHOD CLOSE :AFTER (CCL::BASIC-STREAM)>) #<CCL::STANDARD-KERNEL-METHOD CLOSE (STREAM)>)
        ARGS = 9740068
        CAR-METHS = (#<CCL::STANDARD-KERNEL-METHOD CLOSE :BEFORE (CCL::BASIC-OUTPUT-STREAM)>)
        CELL-2 = (#<CCL::STANDARD-KERNEL-METHOD CLOSE :BEFORE (CCL::BASIC-OUTPUT-STREAM)> . 9740068)
        MAGIC = (NIL #<CCL::STANDARD-KERNEL-METHOD CLOSE :BEFORE (CCL::BASIC-OUTPUT-STREAM)> . 9740068)
  3: (NIL #<Unknown Arguments>)
      [No Locals]
  4: (CCL::%%CHECK-KEYWORDS #(1 #(:ABORT) #<Combined-Method CLOSE #x30200046016F>) 9740082)
      Locals:
        VECTOR-ARG = #(1 #(:ABORT) #<Combined-Method CLOSE #x30200046016F>)
        ARGS = 9740082
        #:G134920 = 1
        ARGS-LIST = (#<BASIC-CHARACTER-OUTPUT-STREAM UTF-8 (PIPE/15) #x302001B116AD>)...

[Stas Boukarev (stassats)]

Try :element-type '(unsigned-byte 8)?

[Martin Buchmann (martin-b77)]

That's what I did in the first place but ccl complained that it was expecting a character stream.

[Stas Boukarev (stassats)]

Ok, then maybe just try writing characters instead?

[Martin Buchmann (martin-b77)]

That's what I did, see comment #8. But it is still leading to a broken pipe error.

[Martin Buchmann (martin-b77)]

I am not sure, if this leads to anything. But I tried to use dtruss to see what is happening between SBCL and ffmpeg when the error occurs. Here are the last lines of output, respectively. As I have never used it before and know nearly nothing about the syscalls, I can hardly interpret this.

SBCL

write(0x7, "\0", 0x1000) = -1 Err#32
__pthread_sigmask(0x1, 0x0, 0x11FEDDC) = 0 0
__pthread_sigmask(0x1, 0x0, 0x11FEDAC) = 0 0
__pthread_sigmask(0x1, 0x0, 0x11FEDAC) = 0 0
__pthread_sigmask(0x2, 0x13AF08, 0x0) = 0 0
__pthread_sigmask(0x1, 0x13AF00, 0x0) = 0 0
sigreturn(0x11FF3D0, 0x1E, 0x27F9CA51B94AFEEE) = 0 Err#-2
__pthread_sigmask(0x1, 0x0, 0x11FEDDC) = 0 0
__pthread_sigmask(0x1, 0x0, 0x11FEDAC) = 0 0
__pthread_sigmask(0x1, 0x0, 0x11FEDAC) = 0 0
__pthread_sigmask(0x2, 0x13AF08, 0x0) = 0 0
wait4(0x520, 0x13FFFF0, 0x13) = 1312 0
__pthread_sigmask(0x1, 0x13AF00, 0x0) = 0 0
sigreturn(0x11FF3D0, 0x1E, 0x27F9CA51B94AFEEE) = 0 Err#-2
write(0x2, "\n\0", 0x1) = 1 0

ffmpeg

write_nocancel(0x2, "\033[0;32musing mv_range_thread = 24\n\033[0m\0", 0x26) = 38 0
psynch_cvwait(0x7F80DF00C048, 0x10100000200, 0x100) = -1 Err#260
psynch_cvwait(0x7F80DF00C1E0, 0x10100000200, 0x100) = -1 Err#260
psynch_cvwait(0x7F80DF00C0D0, 0x10100000200, 0x100) = -1 Err#260
psynch_cvwait(0x7F80DF00C158, 0x10100000200, 0x100) = -1 Err#260
psynch_cvwait(0x7F80DF00C2F0, 0x10100000200, 0x100) = -1 Err#260
psynch_cvwait(0x7F80DF00C268, 0x10100000200, 0x100) = -1 Err#260
psynch_cvwait(0x7F80DF00C378, 0x10100000200, 0x100) = -1 Err#260
psynch_cvwait(0x7F80DF00C400, 0x10100000200, 0x100) = -1 Err#260

[Stas Boukarev (stassats)]

Here's a working CCL version:

(defparameter *width* 640)
(defparameter *height* 480)

(defparameter *ffmpeg-args*
  (list "-loglevel" "debug"
        "-nostats"
        "-nostdin"
        "-f" "rawvideo"
        "-s" (format nil "~Dx~D" *width* *height*)
        "-pix_fmt" "bgra"
        "-r" (format nil "~D" 25)
        "-i" "-"
        "-an"
        "-f" "mp4"
        "-pix_fmt" "yuv420p"
        "-c:v" "libx264"
        "-profile:v" "main"
        "-level" "3.1"
        "-y"
        "out.mp4"))

(defparameter *p*
  (ccl:run-program "ffmpeg" *ffmpeg-args*
                   :input :stream :output t :error :output :wait nil
                   :element-type '(unsigned-byte 8)))

(let ((buffer (make-array (* *width* *height* 4)
                          :element-type '(unsigned-byte 8) :initial-element 255)))

  (dotimes (i 50)
    (write-sequence buffer (ccl:external-process-input-stream *p*)))
  (close (ccl:external-process-input-stream *p*)))

[Martin Buchmann (martin-b77)]

Thanks for clarification where to put the element-type statement and sorry for my misunderstand. But it is still not working for me:

on #<BASIC-BINARY-OUTPUT-STREAM UTF-8 (PIPE/15) #x3020013E9DBD> :
Broken pipe during write
   [Condition of type CCL::SIMPLE-STREAM-ERROR]

Restarts:
 0: [RETRY] Retry SLIME interactive evaluation request.
 1: [*ABORT] Return to SLIME's top level.
 2: [ABORT-BREAK] Reset this thread
 3: [ABORT] Kill this thread

Backtrace:
  0: (#<CCL::STANDARD-KERNEL-METHOD CCL::STREAM-IO-ERROR (STREAM T T)> #<BASIC-BINARY-OUTPUT-STREAM UTF-8 (PIPE/15) #x3020013E9DBD> 32 "write")
      Locals:
        STREAM = #<BASIC-BINARY-OUTPUT-STREAM UTF-8 (PIPE/15) #x3020013E9DBD>
        ERROR-NUMBER = 32
        CONTEXT = "write"
  1: (CCL::FD-STREAM-FORCE-OUTPUT #<BASIC-BINARY-OUTPUT-STREAM UTF-8 (PIPE/15) #x3020013E9DBD> #S(CCL::IOBLOCK :STREAM #<BASIC-BINARY-OUTPUT-STREAM UTF-8 (PIPE/15) #x3020013E9DBD> :UNTYI-CHAR NIL ..) 512 N..
      Locals:
        S = #<BASIC-BINARY-OUTPUT-STREAM UTF-8 (PIPE/15) #x3020013E9DBD>
        IOBLOCK = #S(CCL::IOBLOCK :STREAM #<BASIC-BINARY-OUTPUT-STREAM UTF-8 (PIPE/15) #x3020013E9DBD> :UNTYI-CHAR NIL :INBUF ...)
        COUNT = 512
        FINISH-P = NIL
        FD = 15
        IO-BUFFER = #<IO-BUFFER (UNSIGNED-BYTE 8) 0/0/512 #x3020013E9BBD>
        BUF = #<A Foreign Pointer [stack-allocated] #x49001F8>
        OCTETS-TO-WRITE = 512
        OCTETS = 512
        WRITTEN = -32
  2: (CCL::%IOBLOCK-BINARY-STREAM-WRITE-VECTOR #S(CCL::IOBLOCK :STREAM #<BASIC-BINARY-OUTPUT-STREAM UTF-8 (PIPE/15) #x3020013E9DBD> :UNTYI-CHAR NIL :INBUF ...) #(255 255 255 255 255 255 ...) 0 1228800)
      Locals:
        IOBLOCK = #S(CCL::IOBLOCK :STREAM #<BASIC-BINARY-OUTPUT-STREAM UTF-8 (PIPE/15) #x30200128E95D> :UNTYI-CHAR NIL :INBUF ...)
        VECTOR = #(255 255 255 255 255 255 ...)
        START = 0
        END = 1228800
        OUT = #<IO-BUFFER (UNSIGNED-BYTE 8) 0/0/512 #x30200128E75D>
        WRITTEN = 512
        TOTAL = 1228800
        BUFTYPE = 231
        POS = 70144
        LEFT = 1158656
        INDEX = 512
        COUNT = 0
        LIMIT = 512
        BUF = #(255 255 255 255 255 255 ...)
        AVAIL = 512
  3: (WRITE-SEQUENCE #(255 255 255 255 255 255 ...) #<BASIC-BINARY-OUTPUT-STREAM UTF-8 (PIPE/15) #x3020013E9DBD> :START 0 :END 1228800)
      Locals:
        CCL::SEQ = #(255 255 255 255 255 255 ...)
        STREAM = #<BASIC-BINARY-OUTPUT-STREAM UTF-8 (PIPE/15) #x30200128E95D>
        CCL::START = 0
        CCL::END = 1228800
        VECTOR = #(255 255 255 255 255 255 ...)
        CCL::OFFSET = 0

I was really hoping that I was just missing something obvious. Is this working for you under macOS 10.15.?

[Stas Boukarev (stassats)]

Yes, working fine with SBCL and CCL, even played with it and produced some nice looking static noise with it. So, there's something going on with your OS configuration.

[Martin Buchmann (martin-b77)]

Well, thanks a lot for your efforts! I am not aware of having anything special with my OS configuration but I guess, that doesn't mean much.

I have installed SBCL using macports and gave it full disc access in the security System Preferences. Do you have any idea how I could further check what is going on?

[Stas Boukarev (stassats)]

Can you write the output to a file and then do "cat file | ffmpeg --args"?

[Martin Buchmann (martin-b77)]

It really looks like something is wrong with ffmpeg installed via macports on Catalina. I can write the data to a binary file and pipe this to ffmpeg using cat as suggested without problems under macOS 10.13. Using macOS 10.15. ffmpeg fails with a segmentation fault. It is running fine with other tasks so I was assuming ffmpeg is working.

Thanks you so much for helping me finding the right track. Sorry for causing all this trouble. I am pretty sure that you can close this bug report as it is not caused by SBCL.