AI: API: Add audio_frames and video_frames to HTTP API. v7.0.122 (#4559)

[ossrs-ai]

This PR adds separate audio and video frame counting to the HTTP API (/api/v1/streams/) for better stream observability. The API now reports three frame fields:

• frames - Total frames (video + audio)
• video_frames - Video frames/packets only
• audio_frames - Audio frames/packets only

This enhancement provides better visibility into stream composition and helps detect issues with CBR/VBR streams, audio/video sync problems, and codec-specific behavior.

Before:

{
  "streams": [
    {
      "frames": 0, // video frames.
    }
  ]
}

After:

{
  "streams": [
    {
      "frames": 6912, // video frames.
      "audio_frames": 5678, // audio frames.
      "video_frames": 1234, // video frames.
    }
  ]
}

Frame Counting Strategy

• All protocols report frames every N frames to balance accuracy and performance
• Frames are counted at the protocol-specific message/packet level:
  • RTMP: Counts RTMP messages (video/audio)
  • WebRTC: Counts RTP packets (video/audio)
  • SRT: Counts MPEG-TS messages (H.264/HEVC/AAC)