fix: single-pass NVENC encode for selfbot stream (no double encode)

Address review: the capture ffmpeg had no -b:v, so it encoded at nvenc's
low default (~2.47 Mbps) and the library then re-encoded to 8 Mbps, which
only upscaled already-lost detail. The double encode also kept CPU decode
+ scale + re-encode in the library, contradicting the "GPU handles it"
claim.

Now the system ffmpeg produces the final Discord-ready H264 in one pass
(-b:v/-maxrate at the configured bitrate, -bf 0, 1s keyframes, yuv420p,
-forced-idr) and prepareStream uses noTranscoding:true to remux only. One
GPU encode, no library decode/scale/re-encode.

Verified locally: high-motion source fills 8.7 Mbps at these args (vs the
~2.47 Mbps no-bitrate default), real :1 desktop holds 60fps at realtime,
and the capture -> copy/remux chain yields h264 1920x1080 yuv420p 60fps
has_b_frames=0. tsc --noEmit passes. Live Discord test pending reboot.

bot/src/stream/selfbot.ts

@@ -46,9 +46,9 @@ export class SelfbotStreamer implements ScreenStreamer {
           `원본 오류: ${(e as Error).message}`,
       );
     }
-    if (!vs.Streamer || !vs.prepareStream || !vs.playStream || !vs.Encoders) {
+    if (!vs.Streamer || !vs.prepareStream || !vs.playStream) {
       throw new Error(
-        "@dank074/discord-video-stream v6 API(Streamer/prepareStream/playStream/Encoders)를 찾지 못했습니다. " +
+        "@dank074/discord-video-stream v6 API(Streamer/prepareStream/playStream)를 찾지 못했습니다. " +
           "package.json 버전을 ^6.0.0으로 맞추세요.",
       );
     }
@@ -64,7 +64,7 @@ export class SelfbotStreamer implements ScreenStreamer {
       return "셀프봇 송출은 음성 채널 안에서 호출해야 합니다.";
     }
     const { selfbot, vs } = await this.loadLib();
-    const { Streamer, prepareStream, playStream, Encoders } = vs;
+    const { Streamer, prepareStream, playStream } = vs;
 
     this.streamer = new Streamer(new selfbot.Client());
     await this.streamer.client.login(this.config.selfbotToken);
@@ -78,13 +78,17 @@ export class SelfbotStreamer implements ScreenStreamer {
     // bundled libav for the x11grab input device is not portable; piping the
     // system ffmpeg is. (Verified live against a real voice channel.)
     //
-    // With streamHw on (default) the capture is encoded by the GPU
-    // (h264_nvenc, RTX 5050) so 1080p60 stays smooth without loading the CPU;
-    // the library then transcodes with NVENC too (see encoder below). Without
-    // hardware support we fall back to software x264.
+    // The SYSTEM ffmpeg produces the final, Discord-ready H264 in one pass:
+    // target bitrate (-b:v/-maxrate), no B-frames (WebRTC requires this), a
+    // 1s keyframe interval, and yuv420p. The library then only REMUXES it
+    // (noTranscoding below) so there is no second decode/scale/encode. With
+    // streamHw on (default) this single encode runs on the GPU (h264_nvenc,
+    // RTX 5050); otherwise it falls back to software x264.
     const hw = this.config.streamHw;
+    const kbps = this.config.vncBitrateKbps;
+    const maxKbps = Math.round(kbps * 1.5);
     const captureCodecArgs = hw
-      ? ["-c:v", "h264_nvenc", "-preset", "p4", "-tune", "ll"]
+      ? ["-c:v", "h264_nvenc", "-preset", "p4", "-tune", "ll", "-forced-idr", "1"]
       : ["-c:v", "libx264", "-preset", "ultrafast", "-tune", "zerolatency"];
     const capture = spawn("ffmpeg", [
       "-loglevel", "error",
@@ -93,7 +97,10 @@ export class SelfbotStreamer implements ScreenStreamer {
       "-video_size", this.config.vncResolution,
       "-i", this.config.vncDisplay,
       ...captureCodecArgs,
-      "-pix_fmt", "yuv420p", "-g", String(this.config.vncFramerate),
+      "-b:v", `${kbps}k`, "-maxrate", `${maxKbps}k`, "-bufsize", `${kbps}k`,
+      "-bf", "0",
+      "-pix_fmt", "yuv420p",
+      "-g", String(this.config.vncFramerate),
       "-f", "mpegts", "pipe:1",
     ]);
     this.capture = capture;
@@ -104,13 +111,15 @@ export class SelfbotStreamer implements ScreenStreamer {
     const { command, output } = prepareStream(
       capture.stdout,
       {
+        // The capture above is already a Discord-ready H264 elementary stream,
+        // so the library only remuxes it (no second encode). width/height/
+        // frameRate are passed for signalling; encoding options are ignored
+        // on the copy path.
         width: w || 1920,
         height: h || 1080,
         frameRate: this.config.vncFramerate,
         videoCodec: "H264",
-        bitrateVideo: this.config.vncBitrateKbps,
-        bitrateVideoMax: Math.round(this.config.vncBitrateKbps * 1.5),
-        encoder: hw ? Encoders.nvenc() : Encoders.software(),
+        noTranscoding: true,
       },
       this.controller.signal,
     );