/// <summary>
/// Gets the manifest containing information about available closed caption tracks on the specified video.
/// </summary>
public async ValueTask <ClosedCaptionManifest> GetManifestAsync(
VideoId videoId,
CancellationToken cancellationToken = default)
{
var videoInfo = await _controller.GetVideoInfoAsync(videoId, cancellationToken);
var playerResponse =
videoInfo.TryGetPlayerResponse() ??
throw new YoutubeExplodeException("Could not extract player response.");
var trackInfos = playerResponse
.GetClosedCaptionTracks()
.Select(t =>
{
var url =
t.TryGetUrl() ??
throw new YoutubeExplodeException("Could not extract track URL.");
var languageCode =
t.TryGetLanguageCode() ??
throw new YoutubeExplodeException("Could not extract track language code.");
var languageName =
t.TryGetLanguageName() ??
throw new YoutubeExplodeException("Could not extract track language name.");
var isAutoGenerated = t.IsAutoGenerated();
return(new ClosedCaptionTrackInfo(
url,
new Language(languageCode, languageName),
isAutoGenerated
));
})
.ToArray();
return(new ClosedCaptionManifest(trackInfos));
}
private async ValueTask PopulateStreamInfosAsync(
ICollection <IStreamInfo> streamInfos,
VideoId videoId,
CancellationToken cancellationToken = default)
{
var watchPage = await _controller.GetVideoWatchPageAsync(videoId, cancellationToken);
// Try to get player source (failing is ok because there's a decent chance we won't need it)
var playerSourceUrl = watchPage.TryGetPlayerSourceUrl();
var playerSource = !string.IsNullOrWhiteSpace(playerSourceUrl)
? await _controller.GetPlayerSourceAsync(playerSourceUrl, cancellationToken)
: null;
var signatureScrambler = playerSource?.TryGetSignatureScrambler() ?? SignatureScrambler.Null;
var playerResponseFromWatchPage = watchPage.TryGetPlayerResponse();
if (playerResponseFromWatchPage is not null)
{
var purchasePreviewVideoId = playerResponseFromWatchPage.TryGetPreviewVideoId();
if (!string.IsNullOrWhiteSpace(purchasePreviewVideoId))
{
throw new VideoRequiresPurchaseException(
$"Video '{videoId}' requires purchase and cannot be played.",
purchasePreviewVideoId
);
}
if (playerResponseFromWatchPage.IsVideoPlayable())
{
// Extract streams from watch page
await PopulateStreamInfosAsync(
streamInfos,
watchPage.GetStreams(),
signatureScrambler,
cancellationToken
);
// Extract streams from player response
await PopulateStreamInfosAsync(
streamInfos,
playerResponseFromWatchPage.GetStreams(),
signatureScrambler,
cancellationToken
);
// Extract streams from DASH manifest
var dashManifestUrlRaw = playerResponseFromWatchPage.TryGetDashManifestUrl();
if (!string.IsNullOrWhiteSpace(dashManifestUrlRaw))
{
var dashManifestUrl = UnscrambleDashManifestUrl(signatureScrambler, dashManifestUrlRaw);
var dashManifest = await _controller.GetDashManifestAsync(dashManifestUrl, cancellationToken);
await PopulateStreamInfosAsync(
streamInfos,
dashManifest.GetStreams(),
signatureScrambler,
cancellationToken
);
}
}
// If successfully retrieved streams, return
if (streamInfos.Any())
{
return;
}
}
// Try to get streams from video info
// Note: it seems YouTube has stopped using get_video_info and replaced it with an
// internal API endpoint that resolves player response directly.
// This may be an area for future improvement.
var signatureTimestamp = playerSource?.TryGetSignatureTimestamp() ?? "";
var videoInfo = await _controller.GetVideoInfoAsync(videoId, signatureTimestamp, cancellationToken);
var playerResponseFromVideoInfo = videoInfo.TryGetPlayerResponse();
if (playerResponseFromVideoInfo is not null)
{
if (playerResponseFromVideoInfo.IsVideoPlayable())
{
// Extract streams from video info
await PopulateStreamInfosAsync(
streamInfos,
videoInfo.GetStreams(),
signatureScrambler,
cancellationToken
);
// Extract streams from player response
await PopulateStreamInfosAsync(
streamInfos,
playerResponseFromVideoInfo.GetStreams(),
signatureScrambler,
cancellationToken
);
// Extract streams from DASH manifest
var dashManifestUrlRaw = playerResponseFromVideoInfo.TryGetDashManifestUrl();
if (!string.IsNullOrWhiteSpace(dashManifestUrlRaw))
{
var dashManifestUrl = UnscrambleDashManifestUrl(signatureScrambler, dashManifestUrlRaw);
var dashManifest = await _controller.GetDashManifestAsync(dashManifestUrl, cancellationToken);
await PopulateStreamInfosAsync(
streamInfos,
dashManifest.GetStreams(),
signatureScrambler,
cancellationToken
);
}
// If successfully retrieved streams, return
if (streamInfos.Any())
{
return;
}
}
else
{
var errorMessage = playerResponseFromVideoInfo.TryGetVideoPlayabilityError();
throw new VideoUnplayableException($"Video '{videoId}' is unplayable. Reason: {errorMessage}.");
}
}
// Couldn't extract any streams
throw new VideoUnplayableException($"Video '{videoId}' does not contain any playable streams.");
}