# Service quality

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You can use service quality callbacks to notify users about video, audio, and screen sharing quality during a session and unstable network conditions. You can also use these to measure or show latency, FPS, and resolution. Zoom Video SDK optimizes the FPS and resolution to the current device and network capabilities to optimize a good, smooth experience.

Additionally, you can build network strength indicators for your users or a real-time statistics dashboard of video, audio, and screen share quality. This is similar to [how Zoom Meetings shares diagnostic information](https://support.zoom.com/hc/en/article?id=zm_kb&sysparm_article=KB0070504).

If you want near real time analytics to quickly diagnose and resolve network disruptions, consider purchasing a [Quality of Service Subscription (QSS) plan](https://www.zoom.com/en/services/qss/) to use our [QSS API](/docs/api/qss/#tag/video-sdk-sessions/get/videosdk/sessions/{sessionId}/users/qos_summary) and [webhooks](/docs/api/qss/events/#tag/session) for Video SDK.

## Network status

The [`ZoomVideoSDKNetworkStatus`](https://marketplacefront.zoom.us/sdk/custom/ios/_zoom_video_s_d_k_constants_8h.html#aef71ee4668bf0f030240ac22dfc67826) enum includes values representing the network status.

```objectivec
ZoomVideoSDKNetworkStatus_None,
ZoomVideoSDKNetworkStatus_Bad,
ZoomVideoSDKNetworkStatus_Normal,
ZoomVideoSDKNetworkStatus_Good
```

To get a network status change callback, there must be at least two users in the session with their video on. You can use the network status returned from the callback to create an icon to show the current network quality.

```swift
func onUserVideoNetworkStatusChanged(_ status: ZoomVideoSDKNetworkStatus, user: ZoomVideoSDKUser) {
    if status == .bad {
      //Do something
    }
}
```

```objectivec
- (void)onUserVideoNetworkStatusChanged:(ZoomVideoSDKNetworkStatus)status user:(ZoomVideoSDKUser *)user {
    if (status == ZoomVideoSDKNetworkStatus_Bad) {
      //Do something
    }
}
```

## QOS statistics

The [`onQOSStatisticsReceived`](https://marketplacefront.zoom.us/sdk/custom/ios/protocol_zoom_video_s_d_k_delegate-p.html#aadbb25dd2ca06bcf1e6b9edc34489b76) callback provides real-time quality-of-service metrics for audio, video, and screen sharing streams. It fires for both send and receive directions, identified by the `direction` property on the statistics object.

The base [`ZoomVideoSDKQOSStatistics`](https://marketplacefront.zoom.us/sdk/custom/ios/interface_zoom_video_s_d_k_q_o_s_statistics.html) object contains fields common to all stream types and directions. Depending on the value of `direction`, cast the object to [`ZoomVideoSDKQOSSendStatistics`](https://marketplacefront.zoom.us/sdk/custom/ios/interface_zoom_video_s_d_k_q_o_s_send_statistics.html) or [`ZoomVideoSDKQOSRecvStatistics`](https://marketplacefront.zoom.us/sdk/custom/ios/interface_zoom_video_s_d_k_q_o_s_recv_statistics.html) to specifically access send or receive fields.

```swift
func onQOSStatisticsReceived(_ statistics: ZoomVideoSDKQOSStatistics, user: ZoomVideoSDKUser) {
    // Common fields available on all statistics
    statistics.direction        // .send or .receive
    statistics.statisticsType   // .audio, .video, or .share
    statistics.codecName        // e.g. "h264", "av1", "opus" — valid only during this callback
    statistics.timestamp
    statistics.rtt
    statistics.jitter
    statistics.width
    statistics.height
    statistics.fps
    statistics.bps
    statistics.packetsLost
    statistics.packetsSent
    statistics.networkLevel
    statistics.avgLoss          // per-thousand, e.g. 100 = 10%
    statistics.maxLoss          // per-thousand
    statistics.bandwidth

    if statistics.direction == .send, let sendStats = statistics as? ZoomVideoSDKQOSSendStatistics {
        sendStats.frameWidthInput
        sendStats.frameHeightInput
        sendStats.frameRateInput
        sendStats.bytesSent
        sendStats.packetsSent
        sendStats.totalPacketSendDelay
        sendStats.totalEncodeTime
        sendStats.framesEncoded
    } else if statistics.direction == .receive, let recvStats = statistics as? ZoomVideoSDKQOSRecvStatistics {
        recvStats.bytesReceived
        recvStats.packetsReceived
        recvStats.estimatedPlayoutTimestamp
        recvStats.totalDecodeTime
        recvStats.framesDecoded
        recvStats.jitterBufferDelay
        recvStats.jitterBufferEmittedCount
    }
}
```

```objectivec
- (void)onQOSStatisticsReceived:(ZoomVideoSDKQOSStatistics *)statistics user:(ZoomVideoSDKUser *)user {
    // Common fields available on all statistics
    statistics.direction;       // ZoomVideoSDKStatisticsDirection_Send or _Receive
    statistics.statisticsType;  // Audio, Video, or Share
    statistics.codecName;       // e.g. "h264", "av1", "opus" — valid only during this callback
    statistics.timestamp;
    statistics.rtt;
    statistics.jitter;
    statistics.width;
    statistics.height;
    statistics.fps;
    statistics.bps;
    statistics.packetsLost;
    statistics.packetsSent;
    statistics.networkLevel;
    statistics.avgLoss;         // per-thousand, e.g. 100 = 10%
    statistics.maxLoss;         // per-thousand
    statistics.bandwidth;

    if (statistics.direction == ZoomVideoSDKStatisticsDirection_Send) {
        ZoomVideoSDKQOSSendStatistics *sendStats = (ZoomVideoSDKQOSSendStatistics *)statistics;
        sendStats.frameWidthInput;
        sendStats.frameHeightInput;
        sendStats.frameRateInput;
        sendStats.bytesSent;
        sendStats.packetsSent;
        sendStats.totalPacketSendDelay;
        sendStats.totalEncodeTime;
        sendStats.framesEncoded;
    } else if (statistics.direction == ZoomVideoSDKStatisticsDirection_Receive) {
        ZoomVideoSDKQOSRecvStatistics *recvStats = (ZoomVideoSDKQOSRecvStatistics *)statistics;
        recvStats.bytesReceived;
        recvStats.packetsReceived;
        recvStats.estimatedPlayoutTimestamp;
        recvStats.totalDecodeTime;
        recvStats.framesDecoded;
        recvStats.jitterBufferDelay;
        recvStats.jitterBufferEmittedCount;
    }
}
```

### Video quality

When `statisticsType` is `.video`, the callback provides video-specific metrics such as frame dimensions, frame rate, and bitrate. To receive video statistics, there must be at least two users in the session with their video on.

### Audio quality

When `statisticsType` is `.audio`, the callback provides audio-specific metrics such as codec, jitter, and packet loss. The `width`, `height`, and `fps` fields are not applicable for audio. To receive audio statistics, there must be at least two users actively sending audio to the session.

### Screen sharing quality

When `statisticsType` is `.share`, the callback provides screen sharing metrics such as frame dimensions, frame rate, and bitrate. To receive share statistics, there must be at least two users in the session with at least one sharing their screen.