Media playback and failover

For live and video-on-demand (VOD) media, TVSDK starts playback by downloading the playlist associated with the middle-resolution bit rate and downloads the media segments defined by that playlist. It quickly selects the high-resolution bit rate playlist and its associated media and continues the downloading process.

Missing playlist failover

When an entire playlist is missing, for example, when the M3U8 file specified in a top-level manifest file does not download, TVSDK attempts to recover. If it cannot be recovered, your application determines the next step.

If the playlist that is associated with the middle-resolution bit rate is missing, TVSDK searches for a variant playlist at the same resolution. If it finds the same resolution, it starts downloading the variant playlist and the segments from the matching position. If TVSDK does not find the same resolution playlist, it will try to cycle through other bitrate playlists and their variants. An immediately lower bitrate is the first choice, then its variant, and so on. If all of the lower bitrate playlists and their variants are exhausted in the attempt to find a valid playlist, TVSDK will go to the top bitrate and count down from there. If a valid playlist cannot be found, the process fails, and the player moves to the ERROR state.

Your application can determine how to handle this situation. For example, you might want to close the player activity and direct the user to the catalog activity. The event of interest is the STATUS_CHANGED event, and the corresponding callback is the onStatusChange method. Here is code that monitors whether the player changes its internal state to ERROR:

For more information, see the PSDKDemo file. Event listeners are attached to the MediaPlayer instance.

case MediaPlayerStatus.ERROR:
Alert.show(event.error.toString(), “Error occurred”);
break;

If the client side network is down, you can use this code to verify.

psdkutils::PSDKString
getNetworkDownVerificationUrl() const { return
_networkDownVerificationUrl; }

API will provide the url that is used to verify if the client side network is down. This should be a valid url, which returns http response code 200 on http requests.

psdkutils::PSDKErrorCode
 setNetworkDownVerificationUrl(psdkutils::PSDKString value) {
_networkDownVerificationUrl = value; return psdkutils::kECSuccess; }

If setNetworkDownVerificationUrl is not set, TVSDK uses the MainManifest url by default to figure if the network is down.

Missing segment failover

When a segment is missing, for example when a particular segment fails to download, TVSDK attempts to recover through a variety of failover attempts. If it cannot recover, it issues an error.

If a segment is missing on the server because, for example, the manifest file is not present, the segment cannot be downloaded, and so on, TVSDK attempts to fail over by trying the following options:

1. Attempt a failover to the same segment, at the same bit rate, in a variant file.
2. Switch to an alternate bit rate (ABR switch) in the same file.
3. Cycle through every available bit rate in every available variant.
4. Skip the segment and issue a warning.

When TVSDK cannot obtain an alternative segment, it triggers a CONTENT_ERROR error notification. This notification contains an inner notification with the code DOWNLOAD_ERROR code. If the stream with the problem is an alternate audio track, TVSDK generates the AUDIO_TRACK_ERROR error notification.

If the video engine is continuously unable to obtain segments, it limits continuous segment skips to 5, after which playback is stopped and TVSDK issues a NATIVE_ERROR with the code 5.

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