Fix FFMpeg API compatibility for modern FFMpeg 6.x

[Copilot]

This PR resolves issue #78 by updating FFMpegWrapper.cpp to use the modern FFMpeg API, fixing compilation errors with FFMpeg 6.x.

Issues Fixed

The original code used deprecated FFMpeg APIs that were removed in recent versions:

1. av_register_all() removed: This function was deprecated in FFMpeg 4.0 and removed in 5.0+
2. Type mismatch: avcodec_find_decoder() now returns const AVCodec * instead of AVCodec *
3. Channel API changes: channels field replaced with ch_layout.nb_channels in both AVCodecParameters and AVFrame
4. Channel layout functions: av_get_default_channel_layout() deprecated in favor of av_channel_layout_default()

Changes Made

• Removed deprecated registration: Replaced av_register_all() call with explanatory comment (auto-registration since FFMpeg 4.0)
• Fixed decoder type: Changed AVCodec *decoder to const AVCodec *decoder
• Updated channel access: Replaced all instances of ->channels with ->ch_layout.nb_channels
• Modernized channel layout setup:
  • Replaced channel_layout field checks with ch_layout equivalents
  • Updated from av_get_default_channel_layout() to av_channel_layout_default()
  • Changed SWR context setup from av_opt_set_int() with *_channel_layout to av_opt_set_chlayout() with *_chlayout
• Added required header: Included <libavutil/channel_layout.h> for new channel layout API

Testing

• Successfully compiles with FFMpeg 6.1.1 (libavcodec 60.31.102)
• All changes maintain existing functionality while using the modern API
• Built and tested anmp-dump binary executes correctly

Backward Compatibility

These changes target FFMpeg 4.0+ API. The new channel layout API was introduced in FFMpeg 5.1, but the other changes (removing av_register_all(), const correctness) are compatible with FFMpeg 4.0+.

Closes #78

Warning

Firewall rules blocked me from connecting to one or more addresses (expand for details)

I tried to connect to the following addresses, but was blocked by firewall rules:

• esm.ubuntu.com
  • Triggering command: /usr/lib/apt/methods/https (dns block)

If you need me to access, download, or install something from one of these locations, you can either:

• Configure Actions setup steps to set up my environment, which run before the firewall is enabled
• Add the appropriate URLs or hosts to the custom allowlist in this repository's Copilot coding agent settings (admins only)

---

💡 You can make Copilot smarter by setting up custom instructions, customizing its development environment and configuring Model Context Protocol (MCP) servers. Learn more Copilot coding agent tips in the docs.