diff --git a/src/OpenIPC.Viewer.Video/Recording/FfmpegRecordingSession.cs b/src/OpenIPC.Viewer.Video/Recording/FfmpegRecordingSession.cs
index c2e8b7e..7db3897 100644
--- a/src/OpenIPC.Viewer.Video/Recording/FfmpegRecordingSession.cs
+++ b/src/OpenIPC.Viewer.Video/Recording/FfmpegRecordingSession.cs
@@ -94,7 +94,15 @@ public void Start()
         // no row reaches the Recordings tab while REC keeps "running" (#91).
         psi.ArgumentList.Add(FfmpegCliOptions.RtspTimeoutFlag(_ffmpegPath)); psi.ArgumentList.Add(RtspTimeoutMicros);
         psi.ArgumentList.Add("-i"); psi.ArgumentList.Add(BuildRtspUri(_options.RtspUri, _options.Credentials).ToString());
-        psi.ArgumentList.Add("-c"); psi.ArgumentList.Add("copy");
+        // Video is copied untouched. Audio is re-encoded to AAC: OpenIPC cameras
+        // commonly send G.711 (pcm_alaw/pcm_mulaw), which mp4 has no tag for, and
+        // a plain "-c copy" failed the header write so nothing was recorded. AAC at
+        // 8-16 kHz costs next to no CPU. "0:a?" keeps silent cameras working, and
+        // mapping only video+audio drops ONVIF metadata/data tracks mp4 rejects too.
+        psi.ArgumentList.Add("-map"); psi.ArgumentList.Add("0:v");
+        psi.ArgumentList.Add("-map"); psi.ArgumentList.Add("0:a?");
+        psi.ArgumentList.Add("-c:v"); psi.ArgumentList.Add("copy");
+        psi.ArgumentList.Add("-c:a"); psi.ArgumentList.Add("aac");
         psi.ArgumentList.Add("-f"); psi.ArgumentList.Add("segment");
         psi.ArgumentList.Add("-segment_time"); psi.ArgumentList.Add(((int)_options.SegmentDuration.TotalSeconds).ToString(System.Globalization.CultureInfo.InvariantCulture));
         psi.ArgumentList.Add("-reset_timestamps"); psi.ArgumentList.Add("1");
diff --git a/src/OpenIPC.Viewer.Video/Recording/LibavformatRecordingSession.cs b/src/OpenIPC.Viewer.Video/Recording/LibavformatRecordingSession.cs
index dc8eb29..58e2ffe 100644
--- a/src/OpenIPC.Viewer.Video/Recording/LibavformatRecordingSession.cs
+++ b/src/OpenIPC.Viewer.Video/Recording/LibavformatRecordingSession.cs
@@ -163,6 +163,7 @@ private unsafe void Run()
             outputCtx = outRaw;
 
             streamMap = new int[(int)inputCtx->nb_streams];
+            var hasVideo = false;
             for (var i = 0; i < (int)inputCtx->nb_streams; i++)
             {
                 streamMap[i] = -1;
@@ -171,6 +172,18 @@ private unsafe void Run()
                 if (kind != AVMediaType.AVMEDIA_TYPE_VIDEO && kind != AVMediaType.AVMEDIA_TYPE_AUDIO)
                     continue;
 
+                // OpenIPC cameras commonly send G.711 (pcm_alaw/pcm_mulaw) audio, which
+                // mp4 has no tag for: copying it made avformat_write_header fail with
+                // EINVAL and no recording at all. Drop what the container can't hold;
+                // the video is what a recording is for.
+                var codecId = inStream->codecpar->codec_id;
+                if (ffmpeg.avformat_query_codec(outputCtx->oformat, codecId, ffmpeg.FF_COMPLIANCE_NORMAL) != 1)
+                {
+                    _logger.LogWarning("Recording skips stream {Index}: mp4 cannot hold {Codec}",
+                        i, ffmpeg.avcodec_get_name(codecId));
+                    continue;
+                }
+
                 var outStream = ffmpeg.avformat_new_stream(outputCtx, null);
                 if (outStream == null)
                     throw new InvalidOperationException("avformat_new_stream returned null");
@@ -183,8 +196,14 @@ private unsafe void Run()
                 outStream->codecpar->codec_tag = 0;
 
                 streamMap[i] = (int)outStream->index;
+                hasVideo |= kind == AVMediaType.AVMEDIA_TYPE_VIDEO;
             }
 
+            // Audio is optional, video is not: an audio-only file isn't a recording.
+            // Fail before avio_open so no empty/useless file is left on disk.
+            if (!hasVideo)
+                throw new InvalidOperationException("The camera stream has no video mp4 can hold");
+
             if ((outputCtx->oformat->flags & ffmpeg.AVFMT_NOFILE) == 0)
             {
                 ret = ffmpeg.avio_open(&outputCtx->pb, _outputPath, ffmpeg.AVIO_FLAG_WRITE);