Explain unavailable video decoders and restored capture settings

tools/chatgui-android/app/src/main/java/com/utun/chat/data/StreamPlayerEngine.kt

@@ -22,6 +22,7 @@ import kotlin.concurrent.withLock
 class StreamPlayerEngine(private val group: Long, private val source: Long, private val epoch: Long,
                          private val localPreview: StreamPreview? = null, private val displayDegrees: Int = 0) {
     companion object { private val viewerLock = ReentrantLock() }
+    private class UnsupportedCodec(message: String) : IllegalStateException(message)
     private data class Frame(val pts: Long, val key: Boolean, val width: Int, val height: Int,
                              val rotation: Int, val top: Int?, val revision: Long, val codec: StreamVideoCodec,
                              val config: ByteArray, val data: ByteArray)
@@ -230,7 +231,7 @@ class StreamPlayerEngine(private val group: Long, private val source: Long, priv
                         check(frame.key)
                         val format = frame.codec.decoderFormat(frame.width, frame.height, frame.rotation, frame.config)
                         val name = android.media.MediaCodecList(android.media.MediaCodecList.REGULAR_CODECS).findDecoderForFormat(format)
-                            ?: error("Unsupported decoder ${frame.codec.label} ${frame.width}x${frame.height}")
+                            ?: throw UnsupportedCodec("Unsupported decoder ${frame.codec.label} ${frame.width}x${frame.height}")
                         decoder = MediaCodec.createByCodecName(name)
                         LogManager.addLog("INFO", "video", "viewer codec id=$id type=${frame.codec.label} decoder=$name config=${frame.config.size}")
                         decoder!!.configure(format, surface, null, 0); decoder!!.start()
@@ -282,7 +283,10 @@ class StreamPlayerEngine(private val group: Long, private val source: Long, priv
                 Thread.sleep(5)
             }
         } catch (e: Exception) {
-            if (running) { mutableStatus.value = R.string.stream_failed; LogManager.addLog("ERROR", "stream", "viewer failed id=$id: ${e.message}") }
+            if (running) {
+                mutableStatus.value = if (e is UnsupportedCodec) R.string.stream_decoder_unsupported else R.string.stream_failed
+                LogManager.addLog("ERROR", "stream", "viewer failed id=$id: ${e.message}")
+            }
         } finally {
             NativeLib.streamStop(id)
             try { decoder?.stop(); decoder?.release() }