DrKLO/Telegram · error

%s: sorry, multi-scan output was not compiled in

Error message

%s: sorry, multi-scan output was not compiled in

What it means

cjpeg emits this when the -scans switch is supplied but the binary was compiled without C_MULTISCAN_FILES_SUPPORTED defined (i.e. multi-scan/progressive JPEG output support was compiled out). The tool recognizes the switch, prints this message via fprintf to stderr, and aborts with exit(EXIT_FAILURE). It is a build-configuration mismatch, not a runtime argument error.

Source

Thrown at TMessagesProj/jni/mozjpeg/cjpeg.c:531

    } else if (keymatch(arg, "sample", 2)) {
      /* Set sampling factors. */
      if (++argn >= argc)       /* advance to next argument */
        usage();
      samplearg = argv[argn];
      /* Must delay setting sample factors until after we have processed any
       * colorspace-determining switches, since jpeg_set_colorspace sets
       * default sampling factors.
       */

    } else if (keymatch(arg, "scans", 4)) {
      /* Set scan script. */
#ifdef C_MULTISCAN_FILES_SUPPORTED
      if (++argn >= argc)       /* advance to next argument */
        usage();
      scansarg = argv[argn];
      /* We must postpone reading the file in case -progressive appears. */
#else
      fprintf(stderr, "%s: sorry, multi-scan output was not compiled in\n",
              progname);
      exit(EXIT_FAILURE);
#endif

    } else if (keymatch(arg, "smooth", 2)) {
      /* Set input smoothing factor. */
      int val;

      if (++argn >= argc)       /* advance to next argument */
        usage();
      if (sscanf(argv[argn], "%d", &val) != 1)
        usage();
      if (val < 0 || val > 100)
        usage();
      cinfo->smoothing_factor = val;

    } else if (keymatch(arg, "targa", 1)) {
      /* Input file is Targa format. */

View on GitHub (pinned to 45ab8f4308)

Solutions

  1. Recompile mozjpeg with C_MULTISCAN_FILES_SUPPORTED enabled (ensure jconfig.h / jmorecfg.h do not undef it, and the build system's WITH_MULTISCAN or equivalent option is on).
  2. If you cannot rebuild, drop the -scans option and use a single-scan output instead, or use -progressive only if C_PROGRESSIVE_SUPPORTED is enabled.
  3. Verify the rebuilt binary: run cjpeg -verbose -scans /dev/null on a throwaway input and confirm it no longer exits with this message.

Example fix

# before
cjpeg -scans myscript.txt input.ppm > out.jpg
# after (rebuild with C_MULTISCAN_FILES_SUPPORTED, then)
cjpeg -scans myscript.txt input.ppm > out.jpg
# or, if you cannot rebuild, omit -scans:
cjpeg input.ppm > out.jpg
Defensive patterns

Strategy: validation

Validate before calling

#!/bin/sh
# Guard before invoking cjpeg with -scans: probe whether this build supports it.
printf '' | cjpeg -scans /dev/null 2>/tmp/probe.err >/dev/null
if grep -q 'multi-scan output was not compiled in' /tmp/probe.err 2>/dev/null; then
  echo 'ERROR: this cjpeg build lacks multi-scan support; rebuild or drop -scans' >&2
  exit 1
fi
cjpeg -scans script.txt in.ppm > out.jpg

Type guard

// n/a: cjpeg is a CLI process, not a typed API. Guard at the shell/script layer.

Try / catch

# cjpeg calls exit() directly; there is no in-process exception.
# Wrap as subprocess and check exit code:
if ! cjpeg -scans script.txt in.ppm > out.jpg 2>cjpeg.err; then
  if grep -q 'multi-scan output was not compiled in' cjpeg.err; then
    echo 'rebuild mozjpeg with C_MULTISCAN_FILES_SUPPORTED or drop -scans' >&2
  fi
  exit 1
fi

Prevention

When it happens

Trigger: Running cjpeg with the -scans <scriptfile> option on a mozjpeg/libjpeg build where the C_MULTISCAN_FILES_SUPPORTED macro was left undefined at compile time (e.g. jconfig with the option disabled, or a stripped/minimal build).

Common situations: Cross-compile or embedded builds (such as the TMessagesProj NDK build) where optional codec features are turned off to shrink binary size; upgrading libjpeg/mozjpeg and inheriting a more restrictive jconfig; using a distro-provided cjpeg that was built conservatively.

Related errors

AI-assisted analysis of DrKLO/Telegram@45ab8f4308 (2026-08-14). Data as JSON: /api/errors/b51459e55b6e84ec. Report an issue: GitHub.