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fix(video): drop fflags nobuffer from RTSP opens (#94) #97

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Merged
keyldev merged 1 commit into from
Oct 19, 2026
Merged

fix(video): drop fflags nobuffer from RTSP opens (#94) #97

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5 changes: 4 additions & 1 deletion src/OpenIPC.Viewer.Video/Pipeline/FfmpegVideoSession.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -674,7 +674,10 @@ private unsafe void BuildOpts(AVDictionary** opts)
ffmpeg.av_dict_set(opts, "max_delay", "200000", 0); // 200ms reorder window
ffmpeg.av_dict_set(opts, "buffer_size", "1048576", 0);
ffmpeg.av_dict_set(opts, "reorder_queue_size", "0", 0);
ffmpeg.av_dict_set(opts, "fflags", "nobuffer", 0);
// No "fflags nobuffer": it throws away the packets read while
// avformat_find_stream_info probes, and some NVRs open every session
// with a keyframe that later frames keep referencing (POC 0). Without
// it neither software nor VideoToolbox can decode a frame (#94).
}

private static string BuildUrlWithCredentials(Uri uri, CameraCredentials? creds)
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5 changes: 3 additions & 2 deletions src/OpenIPC.Viewer.Web/Api/LiveFfmpeg.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -26,8 +26,9 @@ public static Process Start(string rtspUrl, bool transcode)
};

// RTSP socket I/O timeout (µs) so a silent camera ends the process
// instead of holding a connection open forever.
var args = new List<string> { "-rtsp_transport", "tcp", RtspTimeoutFlag(), RtspTimeoutMicros, "-fflags", "nobuffer", "-i", rtspUrl };
// instead of holding a connection open forever. No "-fflags nobuffer":
// it drops the session's opening keyframe on some NVRs (#94).
var args = new List<string> { "-rtsp_transport", "tcp", RtspTimeoutFlag(), RtspTimeoutMicros, "-i", rtspUrl };

// Audio rides along in the same stream instead of getting its own ffmpeg
// session: AAC at 64 kbps is around a percent of the video bitrate, so
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