Codec may be innapropriate

The payload of each block in Figure 2 represents one packet of Opus encoded data the way as originally encoded by the Opus encoder.

Information about frame size representing the duration of encoded speech or audio data, number of encoded frames, stereo information, and DTX is embedded into the payload of Opus and not subject to the storage format. It can be extracted from the payload during decoding of the encoded data. During the usage of DTX no blocks are stored when the channel is inactive. Timestamps MUST be used to reassemble the decoded signal in a time-aligned way.

The adaptive nature of the Opus codec allows for an efficient congestion control. The voice mode of Opus at audio sampling rates of , , and always runs with a variable bit rate.

The average bit rate in that mode is dependent on the input signal and will especially decrease during silent periods. The voice mode at audio sampling rates of and Hz and the audio mode may run at a variable or constant bit rate. In either way, the target bit rate of Opus can be adjusted at any point in time and thus allowing for an efficient congestion control. Furthermore, the amount of encoded speech or audio data encoded in a single packet can be used for congestion control since the transmission rate is inversely proportional to these frame sizes.

A lower packet transmission rate reduces the amount of header overhead but at the same time increases latency and error sensitivity and should be done with care. When SDP is used to specify sessions employing the Opus codec, the mapping is as follows:. Example 2: Hz clock rate, maximum packet size of 40 ms, recommended packet size of 40 ms, maximum average bit rate of bps, stereo signals are preferred, FEC is allowed, DTX is not allowed.

When using the offer-answer procedure described in [RFC] to negotiate the use of Opus, the following considerations apply:. All RTP packets using the payload format defined in this specification are subject to the general security considerations discussed in the RTP specification [RFC] and any profile from e.

This payload format transports Opus encoded speech or audio data, hence, security issues include confidentiality, integrity protection, and authentication of the speech or audio itself. The Opus payload format does not have any built-in security mechanisms. This payload format and the Opus encoding do not exhibit any significant non-uniformity in the receiver-end computational load and thus are unlikely to pose a denial-of-service threat due to the receipt of pathological datagrams.

Bradner, S. Schulzrinne, H. Baugher, M. Freed, N. Casner, S. Handley, M. Rosenberg, J. DivX is a commercial codec, while XviD is its open source alternative. The DivX codec can compress lengthy video segments into small sizes while maintaining relatively high visual quality.

However, this video codec has been only gaining popularity and is not yet supported by all the media software. Hardware Acceleration Support. The best option to determine a codec in your video is install free software that will do the job for you. Here are what you should do to identify a codec:. MediaInfo is one of the most popular tools to show you complete information about your multimedia file.

The software will guide you to a site where you can download the necessary codecs. Sometimes it even shows what media player can reproduce video files of a kind. For example, the software suggests using QuickTime to play MP4 files.

GSpot is a choice of advanced users. It provides a huge amount of information about a file. We briefly outline here some use-cases for codec-specific feedback messages.

In each case, there is no clear existing RTCP message which may be used. The RTCP CLF message contains a header identifying the codec by means of the payload type identifier, and the remaining contents and semantics of the message are defined by the codec.

As specified by section 6. At least four octets of FCI must be provided. Within the common packet header for feedback messages as defined in Section 6. CLF messages are sent according to timing rules defined by the codec.

A mixer or translator MAY choose to forward the message, but SHOULD ensure that such forwarded messages are not sent at a rate greater than the receiver's bandwidth for example, a mixer which receives feedback messages from a unicast peer, and forwards those messages to a multicast session may be forced to drop packets ; such a mixer SHOULD understand the semantics of the CLF message for the payload being forwarded, to ensure that the dropped packets do not prevent correct operation of the codec.

The ABNF for rtcp-fb is described in section 4. In this section, we extend the rtcp-fb attribute to include the CLF message. What codec? Where do I get it? How to install? This thread is locked. You can follow the question or vote as helpful, but you cannot reply to this thread. I have the same question Report abuse. Details required :.