Yalantis/uCrop · error · CImgIOException

load_yuv(): File ' ' doesn't contain frame number %u.

Error message

load_yuv(): File '%s' doesn't contain frame number %u.

What it means

To start at first_frame > 0, load_yuv() seeks past (frame_size * first_frame) bytes; if fseek fails, the file is too short to contain that frame. CImg closes the file and throws CImgIOException naming the missing frame index.

Solutions

1. Compute the frame count as filesize / (size_x*size_y + 2*(size_x/cfx)*(size_y/cfy)) and choose first_frame < count
2. Verify size_x, size_y and chroma_subsampling match the actual file - wrong values shift the seek arithmetic
3. Re-download/re-export the file if it is truncated
4. Start from frame 0 to confirm the file parses, then adjust first_frame

Example fix

// before
imgs.load_yuv("clip.yuv", 640, 480, 420, 100, ~0U); // clip has 50 frames
// after
const unsigned int n = fileSize("clip.yuv") / (640*480 + 2*(320*240));
unsigned int first = std::min(100u, n - 1);
imgs.load_yuv("clip.yuv", 640, 480, 420, first, ~0U);

uint64_t frameSize = (uint64_t)w*h + 2*((uint64_t)(w/cfx)*(h/cfy));
uint64_t nFrames = fileSize(path) / frameSize;
if (firstFrame >= nFrames) firstFrame = nFrames ? nFrames - 1 : 0; // clamp

try { imgs.load_yuv(path, w, h, cs, first, last); }
catch (CImgIOException& e) { fprintf(stderr, "frame out of range: %s\n", e.what()); imgs.assign(); }

When it happens

Trigger: load_yuv(filename, w, h, cs, first_frame, ...) with first_frame beyond the number of frames actually present; wrong frame_size assumption (incorrect width/height/subsampling) making the computed seek offset overshoot the file; a truncated file.

Common situations: Hardcoding a start frame from a longer clip; using wrong dimensions so frame_size math is wrong even though the frame exists; truncated download/copy; looping over frames without knowing the file length.

Understand the failure class

Background: "File not found" and ENOENT errors: why libraries can't find a file that should exist — this error's family across 50 libraries.

Related errors

• load_yuv() : Missing data in file
• load_yuv(): Specified chroma subsampling %u is invalid, for…
• load_yuv(): Specified dimensions (%u,%u) are invalid, for…
• load_yuv(): Specified filename is (null).
• cimg::fclose(): Error code

AI-assisted analysis of Yalantis/uCrop@f788b534b4 (2026-09-08). Data as JSON: /api/errors/5bfcea77cb395b18. Report an issue: GitHub.

Appendix: source

Thrown at ucrop/src/main/jni/CImg.h:67221

        nfirst_frame = first_frame<last_frame?first_frame:last_frame,
        nlast_frame = first_frame<last_frame?last_frame:first_frame,
        nstep_frame = step_frame?step_frame:1;

      if (!size_x || !size_y || size_x%cfx || size_y%cfy)
        throw CImgArgumentException(_cimglist_instance
                                    "load_yuv(): Specified dimensions (%u,%u) are invalid, for file '%s'.",
                                    cimglist_instance,
                                    size_x,size_y,filename?filename:"(FILE*)");

      CImg<ucharT> YUV(size_x,size_y,1,3), UV(size_x/cfx,size_y/cfy,1,2);
      std::FILE *const nfile = file?file:cimg::fopen(filename,"rb");
      bool stop_flag = false;
      int err;
      if (nfirst_frame) {
        err = cimg::fseek(nfile,(uint64T)nfirst_frame*(YUV._width*YUV._height + 2*UV._width*UV._height),SEEK_CUR);
        if (err) {
          if (!file) cimg::fclose(nfile);
          throw CImgIOException(_cimglist_instance
                                "load_yuv(): File '%s' doesn't contain frame number %u.",
                                cimglist_instance,
                                filename?filename:"(FILE*)",nfirst_frame);
        }
      }
      unsigned int frame;
      for (frame = nfirst_frame; !stop_flag && frame<=nlast_frame; frame+=nstep_frame) {
        YUV.get_shared_channel(0).fill(0);
        // *TRY* to read the luminance part, do not replace by cimg::fread!
        err = (int)std::fread((void*)(YUV._data),1,(size_t)YUV._width*YUV._height,nfile);
        if (err!=(int)(YUV._width*YUV._height)) {
          stop_flag = true;
          if (err>0)
            cimg::warn(_cimglist_instance
                       "load_yuv(): File '%s' contains incomplete data or given image dimensions "
                       "(%u,%u) are incorrect.",
                       cimglist_instance,
                       filename?filename:"(FILE*)",size_x,size_y);

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