Improve playback, preroll and TV experience

server/internal/emby/client.go

@@ -297,12 +297,16 @@ func (c *Client) PlaybackInfo(
 		"UserId":     {cred.UserID},
 		"IsPlayback": {"true"},
 	}
+	profile := androidTVDeviceProfile(capabilities)
+	if forceTranscode {
+		forceH264TranscodeProfile(profile)
+	}
 	body, err := json.Marshal(map[string]any{
 		"Id": itemID, "UserId": cred.UserID, "IsPlayback": true,
 		"StartTimeTicks": startTicks, "EnableDirectPlay": !forceTranscode,
 		"EnableDirectStream": !forceTranscode, "EnableTranscoding": true,
-		"AllowVideoStreamCopy": true, "AllowAudioStreamCopy": true,
-		"DeviceProfile": androidTVDeviceProfile(capabilities),
+		"AllowVideoStreamCopy": !forceTranscode, "AllowAudioStreamCopy": true,
+		"DeviceProfile": profile,
 	})
 	var requestBody map[string]any
 	if err == nil {
@@ -314,10 +318,6 @@ func (c *Client) PlaybackInfo(
 	if currentPlaySessionID != "" {
 		requestBody["CurrentPlaySessionId"] = currentPlaySessionID
 	}
-	if forceTranscode {
-		profile := requestBody["DeviceProfile"].(map[string]any)
-		profile["DirectPlayProfiles"] = []map[string]string{}
-	}
 	if err == nil {
 		body, err = json.Marshal(requestBody)
 	}

server/internal/emby/client_playback_test.go

@@ -32,3 +32,23 @@ func TestAndroidTVProfileConstrainsCodecLevelAndResolution(t *testing.T) {
 		t.Fatalf("codec profiles = %#v", codecProfiles)
 	}
 }
+
+func TestForcedTranscodeProfileCannotStreamCopyHEVC(t *testing.T) {
+	profile := androidTVDeviceProfile(PlaybackCapabilities{
+		HEVC: true, HEVCMain: true, HEVCMain10: true,
+	})
+	forceH264TranscodeProfile(profile)
+
+	if direct := profile["DirectPlayProfiles"].([]map[string]string); len(direct) != 0 {
+		t.Fatalf("direct profiles = %#v", direct)
+	}
+	transcode := profile["TranscodingProfiles"].([]map[string]string)
+	if len(transcode) != 1 || transcode[0]["VideoCodec"] != "h264" {
+		t.Fatalf("transcoding profiles = %#v", transcode)
+	}
+	for _, codecProfile := range profile["CodecProfiles"].([]map[string]any) {
+		if codecProfile["Codec"] == "hevc" {
+			t.Fatalf("HEVC constraint survived fallback: %#v", codecProfile)
+		}
+	}
+}

server/internal/emby/device_profile.go

@@ -53,6 +53,27 @@ func androidTVDeviceProfile(capabilities PlaybackCapabilities) map[string]any {
 	}
 }
 
+// forceH264TranscodeProfile turns decoder recovery into an actual codec change. Merely
+// removing DirectPlayProfiles is insufficient: Emby may otherwise stream-copy HEVC into
+// the ordinary HLS transcoding profile and hand the failing decoder the same video again.
+func forceH264TranscodeProfile(profile map[string]any) {
+	profile["DirectPlayProfiles"] = []map[string]string{}
+	profile["TranscodingProfiles"] = []map[string]string{
+		{
+			"Container": "ts", "VideoCodec": "h264", "AudioCodec": "aac",
+			"Protocol": "hls", "Type": "Video", "Context": "Streaming",
+		},
+	}
+	profiles, _ := profile["CodecProfiles"].([]map[string]any)
+	h264Profiles := make([]map[string]any, 0, len(profiles))
+	for _, codecProfile := range profiles {
+		if codec, _ := codecProfile["Codec"].(string); codec == "h264" {
+			h264Profiles = append(h264Profiles, codecProfile)
+		}
+	}
+	profile["CodecProfiles"] = h264Profiles
+}
+
 func androidTVSubtitleProfiles() []map[string]string {
 	return []map[string]string{
 		{"Format": "srt", "Method": "External"},