obsproject/obs-studio

OBS Studio 30.1.0-beta1 FTBFS on NixOS due to a sign-compare warning in QSV_Encoder_Internal.cpp

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#10,200 opened on Feb 4, 2024

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Good first issueplatform/linux

Description

Operating System Info

Other

Other OS

NixOS 23.11

OBS Studio Version

30.1.0-beta1

OBS Studio Version (Other)

No response

OBS Studio Log URL

This is a build failure, so no runtime logs are available

OBS Studio Crash Log URL

No response

Expected Behavior

OBS Studio 30.1.0-beta1 should compile successfully.

Current Behavior

OBS Studio 30.1.0-beta1 FTBFS due to a sign-compare warning being raised as an error. Here is the error from the build logs.

obs-studio> /build/source/plugins/obs-qsv11/QSV_Encoder_Internal.cpp:337:50: error: comparison of integer expressions of different signedness: 'int' and 'const uint32_t' {aka 'const unsigned int'} [8;;https://gcc.gnu.org/onlinedocs/gcc/Warning-Options.html#index-Wsign-compare-Werror=sign-compare8;;]
obs-studio>   337 |             (pParams->nWidth * pParams->nHeight) >= pixelcount_4k) {

Steps to Reproduce

  1. Use NixOS 23.11
  2. Create a local package for libdatachannel 0.20.1 (example)
  3. Create a local package for OBS Studio 30.1.0-beta1 (example)
  4. nix build .#obs-studio -L

Anything else we should know?

Line 337 that raises the warning was introduced in this commit:

The build can be coerced to complete successfully by passing -Wno-error=sign-compare to cmake.

Contributor guide

Tech stack
cppc
Domain
desktopbuild system
Issue type
bug
DifficultyEstimated implementation difficulty for a new contributor, from 1 for very small changes to 5 for expert-level work.
2
Estimated timeA rough time range for an experienced contributor to investigate, implement, test, and prepare a pull request.
under 1 hour
Activity statusHow available the issue appears right now: fresh, active, stale, blocked, or waiting on maintainer input.
active
ClarityHow clearly the issue explains the expected change, acceptance criteria, and next step.
clear
Prerequisites
basic C++ knowledgeunderstanding of compiler warningsfamiliarity with cmake
Newbie friendlinessA 1-100 score estimating how approachable this issue is for first-time contributors.
80
Research direction
The issue is a sign compare warning in plugins/obs qsv11/QSV Encoder Internal.cpp at line 337. The warning occurs because (pParams >nWidth * pParams >nHeight) is int and pixelcount 4k is uint32 t. A simple cast or change of variable type should fix it. The commit that introduced the issue is 2874b8f1cc81736e22e75494ffc8a76bdc8a8969. The build can be coerced by passing Wno error=sign compare to cmake, but a proper fix is preferred.