gramps
e37215d9c4
TASK 32·4. A plain MP4 keeps its index (moov) at the end, so a power cut or a killed process left the entire recording unreadable even though every video byte was on disk. The record block now carries `-movflags +frag_keyframe+empty_moov+default_base_moof`: index first, a playable fragment flushed at every keyframe, so an interrupted take plays to the last fragment. Record block only — the FLV stream output has no index and never gets the flags. Rename-on-stop is untouched. Test: `Args_RecordBlock_IsFragmentedMp4_SoACrashKeepsTheFile` asserts the flags on the record block and their absence from the streaming block. Not yet proven on a real interrupted take (kill ffmpeg mid-recording, play the result); the args test is by construction. Docs: task-32 slice 4 ticked with that caveat, TASKS row, output.md record note, HANDOFF. verify.sh: 550 passed (mouse-injection test excluded, desktop in use), 0 warnings.
73 lines
3.4 KiB
C#
73 lines
3.4 KiB
C#
namespace ytLive.Services.Encoder;
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/// <summary>
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/// Builds the FFmpeg command line for a live RTMP push (TASK 4 ship step 3):
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/// raw BGRA frames via stdin (paced by the frame pump — the pump holds a strict
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/// CFR cadence, so <c>-re</c> would only add a second, fighting pacer), real
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/// audio via the named pipe
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/// (TASK 9 — the mixer streams f32le at 48 kHz stereo into <c>\\.\pipe\<name></c>;
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/// WASAPI loopback + the mic ride the pipe instead of the old anullsrc silence),
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/// H.264 + AAC encoding, FLV muxing to the ingestion URL. Pure — the encoder
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/// just starts <c>ffmpeg.exe [Build(...)]</c>.
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/// </summary>
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public static class FfmpegArgs
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{
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public static IReadOnlyList<string> Build(EncoderOptions options, string videoEncoder)
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{
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var args = new List<string>
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{
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"-hide_banner", "-loglevel", "info",
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"-stats", "-stats_period", "0.5",
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"-f", "rawvideo", "-pix_fmt", "bgra",
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"-video_size", $"{options.RawWidth}x{options.RawHeight}",
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"-framerate", options.Fps.ToString(),
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"-i", "pipe:0",
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"-f", "f32le", "-ar", options.AudioSampleRate.ToString(),
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"-ac", options.AudioChannels.ToString(),
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"-i", $@"\\.\pipe\{options.AudioPipeName}",
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};
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// Each output is a self-contained block: its own -map, codec options,
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// format, and destination. Record+stream encodes the video twice off the
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// one raw input pipe (cheap on NVENC).
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if (options.StreamEnabled)
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{
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AddVideoTags(args, options, videoEncoder);
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args.AddRange(["-c:a", "aac", "-b:a", "128k",
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"-ar", options.AudioSampleRate.ToString(), "-ac", options.AudioChannels.ToString()]);
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args.AddRange(["-f", "flv", options.RtmpUrl]);
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}
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if (options.RecordEnabled)
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{
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AddVideoTags(args, options, videoEncoder);
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args.AddRange(["-c:a", "aac",
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"-ar", options.AudioSampleRate.ToString(), "-ac", options.AudioChannels.ToString()]);
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// TASK 32·4: FRAGMENTED mp4. A plain MP4 writes its index (moov) at the end, so a
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// power cut or a killed process leaves the video bytes on disk in a file nothing can
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// open — the whole recording, not the tail. Fragmented writes the index first and
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// flushes a playable fragment at every keyframe, so an interrupted file still plays up
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// to the last fragment. Record block only: the FLV stream output has no index.
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args.AddRange(["-movflags", "+frag_keyframe+empty_moov+default_base_moof"]);
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args.AddRange(["-f", "mp4", options.RecordPath!]);
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}
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return args;
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}
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private static void AddVideoTags(List<string> args, EncoderOptions options, string videoEncoder)
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{
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var gop = options.GopSize;
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args.AddRange(["-map", "0:v", "-map", "1:a"]);
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if (options.RawWidth != options.Width || options.RawHeight != options.Height)
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{
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args.AddRange(["-vf", $"scale={options.Width}:{options.Height}:flags=bilinear,setsar=1"]);
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}
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args.AddRange(["-c:v", videoEncoder]);
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args.AddRange(["-b:v", $"{options.BitrateKbps}k", "-maxrate", $"{options.BitrateKbps}k",
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"-bufsize", $"{options.BitrateKbps * 2}k"]);
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args.AddRange(["-g", gop.ToString(), "-keyint_min", gop.ToString(),
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"-sc_threshold", "0", "-bf", "0", "-pix_fmt", "yuv420p"]);
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}
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}
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