Custom google cast receiver stuck in "Load is in progress" - chromecast

Question

My custom v3 CAF receiver app is successfully playing the first few live & vod assets. After that, it gets into a state were media commands are being queued because "Load is in progress". It is still (successfully) fetching manifests, but MEDIA_STATUS remains "buffering". The log then shows:
[ 4.537s] [cast.receiver.MediaManager] Load is in progress, media command is being queued.
[ 5.893s] [cast.receiver.MediaManager] Buffering state changed, isPlayerBuffering: true old time: 0 current time: 0
[ 5.897s] [cast.receiver.MediaManager] Sending broadcast status message
CastContext Core event: {"type":"MEDIA_STATUS","mediaStatus":{"mediaSessionId":1,"playbackRate":1,"playerState":"BUFFERING","currentTime":0,"supportedMediaCommands":12303,"volume":{"level":1,"muted":false},"currentItemId":1,"repeatMode":"REPEAT_OFF","liveSeekableRange":{"start":0,"end":20.000999927520752,"isMovingWindow":true,"isLiveDone":false}}}
CastContext MEDIA_STATUS event: {"type":"MEDIA_STATUS","mediaStatus":{"mediaSessionId":1,"playbackRate":1,"playerState":"BUFFERING","currentTime":0,"supportedMediaCommands":12303,"volume":{"level":1,"muted":false},"currentItemId":1,"repeatMode":"REPEAT_OFF","liveSeekableRange":{"start":0,"end":20.000999927520752,"isMovingWindow":true,"isLiveDone":false}}}
Fetch finished loading: GET "(manifest url)".
No errors are shown.
Even after closing and restarting the cast session, the issue remains. The cast device itself has to be rebooted to resolve it. It looks like data is kept between sessions.
It could be important to note that the cast receiver app is not published yet. It is hosted on a local network.
My questions are:
What could be the cause of this stuck behavior?
Is there any session data kept between session?
How to fully reset the cast receiver app, without the necessity to restart the cast device.
The receiver app itself is very basic. Other than license wrapping it resembles the vanilla example app:
const { cast } = window;
const TAG = "CastContext";
class CastStore {
static instance = null;
error = observable.box();
framerate = observable.box();
static getInstance() {
if (!CastStore.instance) {
CastStore.instance = new CastStore();
}
return CastStore.instance;
}
get debugLog() {
return this.framerate.get();
}
get errorLog() {
return this.error.get();
}
init() {
const context = cast.framework.CastReceiverContext.getInstance();
const playerManager = context.getPlayerManager();
playerManager.addEventListener(
cast.framework.events.category.CORE,
event => {
console.log(TAG, "Core event: " + JSON.stringify(event));
}
);
playerManager.addEventListener(
cast.framework.events.EventType.MEDIA_STATUS,
event => {
console.log(TAG, "MEDIA_STATUS event: " + JSON.stringify(event));
}
);
playerManager.addEventListener(
cast.framework.events.EventType.BITRATE_CHANGED,
event => {
console.log(TAG, "BITRATE_CHANGED event: " + JSON.stringify(event));
runInAction(() => {
this.framerate.set(`bitrate: ${event.totalBitrate}`);
});
}
);
playerManager.addEventListener(
cast.framework.events.EventType.ERROR,
event => {
console.log(TAG, "ERROR event: " + JSON.stringify(event));
runInAction(() => {
this.error.set(`Error detailedErrorCode: ${event.detailedErrorCode}`);
});
}
);
// intercept the LOAD request to be able to read in a contentId and get data.
this.loadHandler = new LoadHandler();
playerManager.setMessageInterceptor(
cast.framework.messages.MessageType.LOAD,
loadRequestData => {
this.framerate.set(null);
this.error.set(null);
console.log(TAG, "LOAD message: " + JSON.stringify(loadRequestData));
if (!loadRequestData.media) {
const error = new cast.framework.messages.ErrorData(
cast.framework.messages.ErrorType.LOAD_CANCELLED
);
error.reason = cast.framework.messages.ErrorReason.INVALID_PARAM;
return error;
}
if (!loadRequestData.media.entity) {
// Copy the value from contentId for legacy reasons if needed
loadRequestData.media.entity = loadRequestData.media.contentId;
}
// notify loadMedia
this.loadHandler.onLoadMedia(loadRequestData, playerManager);
return loadRequestData;
}
);
const playbackConfig = new cast.framework.PlaybackConfig();
// intercept license requests & responses
playbackConfig.licenseRequestHandler = requestInfo => {
const challenge = requestInfo.content;
const { castToken } = this.loadHandler;
const wrappedRequest = DrmLicenseHelper.wrapLicenseRequest(
challenge,
castToken
);
requestInfo.content = wrappedRequest;
return requestInfo;
};
playbackConfig.licenseHandler = license => {
const unwrappedLicense = DrmLicenseHelper.unwrapLicenseResponse(license);
return unwrappedLicense;
};
// Duration of buffered media in seconds to start/resume playback after auto-paused due to buffering; default is 10.
playbackConfig.autoResumeDuration = 4;
// Minimum number of buffered segments to start/resume playback.
playbackConfig.initialBandwidth = 1200000;
context.start({
touchScreenOptimizedApp: true,
playbackConfig: playbackConfig,
supportedCommands: cast.framework.messages.Command.ALL_BASIC_MEDIA
});
}
}
The LoadHandler optionally adds a proxy (I'm using a cors-anywhere proxy to remove the origin header), and stores the castToken for licenseRequests:
class LoadHandler {
CORS_USE_PROXY = true;
CORS_PROXY = "http://192.168.0.127:8003";
castToken = null;
onLoadMedia(loadRequestData, playerManager) {
if (!loadRequestData) {
return;
}
const { media } = loadRequestData;
// disable cors for local testing
if (this.CORS_USE_PROXY) {
media.contentId = `${this.CORS_PROXY}/${media.contentId}`;
}
const { customData } = media;
if (customData) {
const { licenseUrl, castToken } = customData;
// install cast token
this.castToken = castToken;
// handle license URL
if (licenseUrl) {
const playbackConfig = playerManager.getPlaybackConfig();
playbackConfig.licenseUrl = licenseUrl;
const { contentType } = loadRequestData.media;
// Dash: "application/dash+xml"
playbackConfig.protectionSystem = cast.framework.ContentProtection.WIDEVINE;
// disable cors for local testing
if (this.CORS_USE_PROXY) {
playbackConfig.licenseUrl = `${this.CORS_PROXY}/${licenseUrl}`;
}
}
}
}
}
The DrmHelper wraps the license request to add the castToken and base64-encodes the whole. The license response is base64-decoded and unwrapped lateron:
export default class DrmLicenseHelper {
static wrapLicenseRequest(challenge, castToken) {
const wrapped = {};
wrapped.AuthToken = castToken;
wrapped.Payload = fromByteArray(new Uint8Array(challenge));
const wrappedJson = JSON.stringify(wrapped);
const wrappedLicenseRequest = fromByteArray(
new TextEncoder().encode(wrappedJson)
);
return wrappedLicenseRequest;
}
static unwrapLicenseResponse(license) {
try {
const responseString = String.fromCharCode.apply(String, license);
const responseJson = JSON.parse(responseString);
const rawLicenseBase64 = responseJson.license;
const decodedLicense = toByteArray(rawLicenseBase64);
return decodedLicense;
} catch (e) {
return license;
}
}
}

Answer 1

The handler for cast.framework.messages.MessageType.LOAD should always return:
the (possibly modified) loadRequestData, or
a promise for the (possibly modified) loadRequestData
null to discard the load request (I'm not 100% sure this works for load requests)
If you do not do this, the load request stays in the queue and any new request is queued after the initial one.
In your handler, you return an error if !loadRequestData.media, which will get you into that state. Another possibility is an exception in the load request handler, which will also get you in that state.

Answer 2

I guess we have a different approach and send everything possible through sendMessage, when we loading stuff we create a new cast.framework.messages.LoadRequestData() which we load with playerManager.load(loadRequest).
But I guess that you might be testing this on an integrated Chromecast, we see this problems as well!?
I suggest that you do one or more
Enable gzip compression on all responses!!!
Stop playback playerManager.stop() (maybe in the interseptor?)
Change how the licenseUrl is set
How we set licenseUrl
playerManager.setMediaPlaybackInfoHandler((loadRequestData, playbackConfig) => {
playbackConfig.licenseUrl = loadRequestData.customData.licenseUrl;
return playbackConfig;
}
);