Design & Development

A strange reason for QRhiGraphicsPipeline create failure

27.05.2026 0, ? Design & Development

Recently while learning the Qt RHI graphics rendering framework I encountered a strange problem: QRhiGraphicsPipeline inexplicably returned false on create! During the time this problem appeared, I was debugging the fragment shader, specifically studying HDR display shaders, and frequently toggling Windows HDR on and off. At one point I thought it was a system issue, so I tried switching to SDR, but the error persisted.

Later, after spending some time reverting modifications, I finally isolated the cause…

First, note that the program framework was basically copied from the Qt official documentation example: https://doc.qt.io/qt-6/qtgui-rhiwindow-example.html. The error occurs at the following code location:

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FFmpeg native script building Windows debug version debugging and tracing issues

24.05.2026 0, ? Design & Development

This time I want to record what feels like a rather hardcore problem. Due to the title length limit, it’s impossible to accurately express all the issues. For example, when debugging FFmpeg code with breakpoints and single‑stepping, the code does not execute in order, jumps around unpredictably, and when checking local variables near a breakpoint, their values cannot be displayed correctly, such as this:

The local variable “offset” cannot show its current value and instead displays “Variable is optimized away and not available.” From the literal meaning, we can guess that the compiler optimized the code, such as inlining and removing intermediate variables, so they can no longer be seen.

However, FFmpeg’s configure parameters for building the debug version do include:

–disable-optimizations –enable-debug –disable-stripping

These officially documented debug build parameters. So why do we still encounter all the debugging obstacles described above, which look like the result of compiler optimizations?

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