Revma Stream Configuration Settings

This article describes the basic functionalities of Revma's stream configuration settings. The stream configuration settings can be found under each station's settings>advanced.

TABLE OF CONTENTS

• Output media format
• Output bit rate
• Burst buffer
• Stream history
• Overfill limit
• Metadata delay
• Delay buffer time
• Metadata format
• Loudness
• Serve over HTTPS
• MP4 output

Output media format

This is where you can set a stream's media format to be AAC or MP3. This option is only available in loop channel stations and transcoding relays. Streaming only stations stream in the media format set in the broadcasting tool and simple relays in the media format of their master station.

Output bit rate

This is where you set a stream's bit rate to be anywhere from 32 to 320 kbps. This option is only available in loop channel stations and transcoding relays. Streaming only stations stream in the bit rate set in the broadcasting tool and simple relays in the bit rate of their master station.

Burst buffer

The amount of audio (in miliseconds) that is going to be delivered to users once they connect to a stream. This also indicates how much audio exists in the client buffer. Applies only to IceCast type of streams. The default value is 5000 ms. The minimum value is 100 ms. and the maximum 60000 ms.

This setting applies for each stream separately. In other words, a relay station will not have a burst buffer that equals the burst buffer set on the master station plus the one set on the relay. However, the burst buffer of the master station will affect the total time that a listener is behind from the "real-time" stream. This is because a relay station is, in essence, a listener of the master station itself. For example, if a master station has burst buffer=5sec. and a relay station (simple or transcoding) also has burst buffer=5sec., the relay's listeners will be at least 10 seconds behind from the "real-time" stream. 

This burst buffer setting does not apply for HLS streams. HLS has one preset "burst buffer" value which is 30 seconds. This derives from the fact that an HLS listener will receive 3 chunks upon connecting to the stream and each chunk is 10 seconds long (3 x 10 sec. = 30 sec.).

Stream history

Stream history defines the total time (in seconds) that is stored in the server buffer. This also indicates the maximum amount of time that a listener can be away from the live source. 

In other words, this setting defines how much time of the stream will be "cached" in the server. This is required for when a listener is away from the live source (when a vast ad or a skip track is airing) in order for him/her to return to the live source correctly. The default value is 90 secs. The minimum value is 30 sec. and the maximum 600 sec.

Overfill limit

The maximum time (in seconds) that a listener can receive replaced content (vast ads or fill) in excess of a spot block duration. For example, in a spot block of 90 seconds duration, Revma might receive 120 seconds of content to replace. In that case the overfill value will become 30 seconds. In case the overfill value reaches the overfill limit value, Revma will break the (ad) content and return to the normal stream. 

Overfill limit value will not exceed the 'stream history' value. More specifically, the overfill limit is required to always be at least 30 seconds less than the stream history, as is required by the server for "safety" reasons. The default value is 60 seconds. The minimum value is 0 sec. and the maximum 570 sec.

Metadata delay

The parameter defines the delay between the time that a metadata update request is made and the time it is actually injected into the stream. This only applies to metadata used to trigger ad replacement blocks (midrolls) and not any other type of metadata. The default value is 500 ms. The minimum value is -5000 ms. and the maximum 5000 ms. If the metadata delay is less than 0, then its absolute value should be less than the delay buffer time (in ms.). 

Delay buffer time

This is the server-side buffer, which is required for the server to have time for any extra processes to take place, primarily preparing content for ad replacement. However, it will apply even if there are no ad replacement rules set. This setting is important for mid-rolls but does not have any effect in regards to pre-rolls. The default value is 10 seconds. The minimum value is 0 sec. and the maximum 30 sec.

Metadata format

If the skip service is enabled, this option will adjust the metadata format, only during the skip. The two options of the metadata format for a skip track are "Stream Title" which will be in the form of [streamTitle='title="{someTitle}",artist="{artist}",url="{skip_media_URL_from_WXXX}"';] and "Stream Title and Stream URL" which will be in the form of [streamTitle='{artist} - {title}';StreamUrl='{skip_media_URL_from_WXXX}';].

Loudness

Under Loudness you can define a minimum and a maximum limit to the default list of loudness scale. This settings applies only to Vast and Skip content. By default the minimum is set to -25 LUFS and the maximum to -7 LUFS. This can be altered in order for the Vast or Skip content to be of more specific loudness (i.e. minimum and maximum set to -13 LUFS).

Serve over HTTPS

Secure URL serving the stream URL over HTTPS. This is enabled by default.

MP4 output

Check this in order to enable fragmented MP4 delivery method. In other words, MP4 output needs to be enabled in a stream's settings in order for the HLS streaming URL to be used by clients. MP4 format is only supported for AAC streams.

Note:

Burst buffer + delay buffer time = the time that the client is behind from the stream's real time. This is under the assumption that there are no network delays between the broadcaster/encoder, the Revma infrastructure and the listener.

Example#1: Stream Configuration: Delay buffer time → 10 seconds, Burst buffer → 0 seconds

Example#2: Stream Configuration: Delay buffer time → 10 seconds, Burst buffer time → 5 seconds