Flash Media Live Encoder 3.2 / FAQ

Download the Authentication add-in and install it on Flash Media Server.

Credentials are saved only for each connect-disconnect session and not for a complete encoding session.

No. Default authentication is implemented at the server level, not at the application level. If desired, you can implement a custom server-side access module for application-level authentication.

The selected bitrate represents the average value at which the application should encode; the actual bit rate depends primarily on the content. Complex video sequences require more bits compared to still video. Also, if there is a drop in frame rate, either due to the device or high CPU usage, the actual bitrate will differ.

The selected frame rate represents the average value at which the application should encode; the actual frame rate depends on the frame rate the application is getting from the device. Some devices do not give the video at the desired frame rate. It may be lower or higher. Also, in the Encoding Statistics panel on the Encoding Log tab, check for frame drops. If there are frame drops, make sure CPU usage of the system is not more than 75%.

Make sure the CPU usage of the encoding computer does not exceed 75%. If it does, try increasing the video bitrate or decreasing the video size or frame rate.

Verify the buffer value from the Flash Media Live Encoder publishing statistics. If this value is high, then network conditions are unfavorable, and Flash Media Live Encoder is unable to stream the data to the server. If the buffer value keeps increasing, then Flash Media Live Encoder may crash. Use Auto Adjust to overcome this issue.

By default, you can stream up to 20Mbps of data to the server.

The deinterlace filter is based on a simple vertical blur algorithm and is not very effective at higher video sizes. Adobe suggests that you deinterlace at the hardware level for better quality and performance.

Select a bitrate according to the video content. For large and dynamic video input, you need a higher bitrate. An extremely low bitrate might result in low-quality video and pixilation. For small and relatively still video input, you can use a lower bitrate.

The Base profile uses less CPU power than the Main profile but compromises video quality. If you want high-quality video and you have a good hardware configuration system, use the Main profile; otherwise the encoder might reduce the output fps during the encoding process.

H.264 levels define the limit on the combination of video size, frame rate, and bitrate that the encoder can encode. Changing the H.264 level does not have any impact on video quality and CPU usage. For details, see the Flash Media Live Encoder Help and Wikipedia article on H.264.

Adobe recommends you use the highest available sample rate to get the best quality. The bit rates listed below are only suggestions; actual bit rates vary from case to case.

For music, movies, and mixed content, try the following bit rates:

For speech, dialogue, and meeting content, use the same ranges listed above, but use Mono for the channel setting.

• Make sure that the CPU usage is not above 75% on the computer running Flash Media Live Encoder and on the subscriber computer.
• The buffer length on the subscriber computer should be a non-zero value.
• If the distortions are periodic, reduce the sampling rate.
• Make sure that the capture device is sending good-quality audio.

• Verify that the source is sending video frames without stalling.
• Try increasing the input frame rate. Lower fps video is not as smooth as higher fps video.
• Verify the output frame rate in the Statistics panel on the Encoding Log tab.
• Make sure that there are no frame drops at the encoder level.
• Try reducing the sample rate of the audio or encode only video. If the video quality improves, try switching to a different audio device.
• Determine whether Auto Adjust with the Drop Frames option is enabled. If Auto Adjust with the Drop Frames option is enabled, the video will stall at the subscriber end.
• If the stalling is present only in the live stream and not in the local file, adverse network conditions, such as high latency and bandwidth congestion, might cause the video to stall. Try using Auto Adjust with the Degrade Quality option.

Pixelation occurs when the video bitrate is not sufficient to encode the video. Increasing the video bitrate will usually resolve the issue. Also, if you are using the H.264 base profile, try switching to the Main profile.

• Open a new subscriber and verify that the problem occurs.
• Ensure that the CPU usage of the encoding computer and the subscriber computer is not more than 75%.
• Ensure that the buffer length of the subscriber is a non-zero value.
• A low frame rate can create a perception that video and audio are out of sync. Try encoding at a higher frame rate.

• Ensure that the CPU usage of the encoding computer and the subscriber computer is not more than 75%.
• Verify that the buffer length at the subscriber end is not higher than the set value.
• Try changing the video codec. the Adobe Flash Player runtime buffers 64 frames to play H.264 content.
• Try reducing the frame rate or bitrate. The encoder requires a high processing time for higher video settings, which can result in latency.
• Try using the Auto Adjust feature because adverse network conditions can result in latency.

• Ensure that the CPU usage of the encoding computer and the subscriber computer is not more than 75%.
• Try switching to video-only encoding. The audio device may be sending more audio samples than expected. If so, change the audio device.
• Try switching to audio-only encoding. The video device may be sending frames that have forward timestamps. If so, change the video device.

Auto Adjust is used to adjust video settings dynamically in case of adverse network conditions between Flash Media Live Encoder and Flash Media Server. With Auto Adjust, you can select either the Drop Frames or the Degrade Quality option. Drop Frames will drop video frames at the RTMP end, and Degrade Quality will reduce the bitrate of the encoded stream. The Degrade Quality option affects both the primary and backup stream as well as the file that is being saved. The Drop Frames option adjusts each stream individually. The saved file will not be affected.

This problem occurs because of adverse network conditions. Try reducing the bitrate to work better with the network bandwidth, or try the Auto Adjust feature.

Jittery video occurs if the subscriber buffer empties. Change the buffer size of the subscriber to a non-zero value.

The size of the buffer depends on two factors:

• Desired latency: The larger the buffer, the longer it takes for the stream to start.
• Stream stability: Larger buffers allow the stream to deal with noise and interruptions better on the network. Making the buffer bigger increases the chance that the stream will play through without any stutters, gaps, or other interruptions.

These two factors are conflicting: Ideally the stream should both start quickly and be stable. One way to deal with this situation is to have two different buffer settings, one for when the stream starts and one for when the playback is in progress. This strategy significantly reduces the conflict. It allows a small buffer to be set for fast start, and a longer one to be used to ensure stream stability when playback begins. Because network issues can still affect the initial buffer size, the initial buffer size cannot be arbitrarily small. Adobe recommends always setting the buffer to a non-zero value.

Live applications that use the Live Aggregate Messages feature on Flash Media Server to improve performance need to use a buffer that is at least as long as the delay introduced by the live aggregation. The delay is 500ms (0.5s) by default but can be configured on a per-application basis. If the buffer isn't long enough, the stream will not play back smoothly.

For dynamic bitrate switching, Adobe recommends using a buffer length value that is equal to the keyframe frequency of the encoded video.

Per the MP4 standard, Flash Media Live Encoder creates fragmented F4V files that are optimized for streaming from Flash Media Server. F4V or MP4 playback applications that do not fully conform to the MP4 specification may fail to play.

If the Flash Media Live Encoder process is terminated during encoding, the saved file will be closed improperly and will not be playable.