Category Archives: Tech Industry updates

Stay updated on the latest news on Streaming Media Industry and technology with the articles here.

CDN Support for RTMP Stream Declining

RTMP Streaming Protocol is receiving declining support from Content Delivery Networks CDNs). One major demand that RTMP stream places on CDNs is the requirement of an active connection between Flash Media Player and the viewer on port 1935. This is because RTMP requires a persistent connection. On the other hand streaming protocols such as HLS, DASH and HDS require streaming over HTTP, and do not require much customization, and are easily supported by CDNs. Also, with Flash not being supported by Android and iOS, RTMP use is steadily declining.

Amazon AWS on RTMP Stream

VdoCipher uses AWS CDN for secure video hosting. Amazon AWS supports RTMP Streaming

AWS supports RTMP Streaming through CloudFront

Amazon’s Cloudfront can be used to serve both the media filed and the media player. This is done through two distributions – a web distribution for the media player, and an RTMP distribution for the media files. Essentially media player files are loaded over HTTP, and once the media player is stored locally, it calls the Amazon S3 streaming bucket for media files over RTMP protocol. Cloudfront accepts RTMP requests over port 1935 and port 80.

Highwind CDN

Highwind transitioned from RTMP stream to HTTP in 2012, in the belief that the future of CDN-delivered video is cacheable HTTP Streaming. Because it allows cacheable streaming, HTTP offers considerably greater efficiencies on the server infrastructure side. Highwind also believes that the innovation in HTTP streaming protocols has accelerated, in particular in DASH (Dynamic Adaptive Streaming over HTTP), whereas RTMP has largely stagnated.

Highwinds CDN have stopped support for RTMP Streaming

Highwinds predict that DASH will become the dominant streaming protocol, and have stopped support for RTMP Streaming

Comcast CDN

Comcast had been using their own CDN for 10 years before launching their CDN for video providers in August 2015. Comcast does not support RTMP streams, and only provides support for HTTP based streaming.

Comcast CDN does not support RTMP streaming

Fastly

Fastly only supports streaming over HTTP over a Transport Layer Security, which is more advanced and secure than SSL security. For more secure video hosting, Fastly has added features for content targetting and Edge Authorization – authorization at the localized CDN level, and not at the point of media origin. This makes the process of authentication faster.

Fastly offers Secure video hosting features, but does not use RTMP streaming

Fastly offers Secure video hosting features, but does not use RTMP streaming

HolaCDN

HolaCDN is developed specifically for video delivery, and is designed as an overlay over an existing CDN. HolaCDN offloads video traffic from existing CDN, allowing the existing CDN to be used for non-streaming uses, and as fallback for video streaming. HolaCDN has optimized its CDN for efficient video delivery, claiming to provide faster and cheaper video delivery because of its video-only focus. HolaCDN only supports HTTP based streaming protocols.

HolaCDN for video hosting does not support RTMP streaming

Level3

Level 3 supports RTMP stream as an Input protocol for media files from server to CDN, but only supports HTTP based streaming protocols for video output.

KeyCDN – HLS Streaming

KeyCDN does not support RTMP Streaming

KeyCDN does not support RTMP streaming

KeyCDN does not use RTMP streaming for video delivery to end users. They rely on HTTP Live Streaming (HLS) for their video streaming. Their reason for not supporting RTMP is that iOS does not support Flash Player (which RTMP uses). If the streaming protocol for Live Streaming used by the streaming software is RTMP, you would need to convert the RTMP stream into an HLS stream. The workflow for playing RTMP encoded videos through KeyCDN is as follows:

RTMP Encoder -> Encoding from RTMP to HLS -> Pull Zone (HLS Feature Enabled)

Verizon Digital Media

Verizon Digital Media CDN uses both HTTP and RTMP streaming, although it clearly expects HTTP to continue to be the dominant streaming technology. Verizon will stop support for RTMP in June 2017

Verizons Edgecast CDN plans to discontinue support for RTMP streaming in 2017.

Tech Update: Netflix Updates Codecs Use for Efficient Encoding

Netflix have switched streaming to encoding in H.264 High Profile and VP9 (profile 0), in response to increasing processor capabilities of decoding streams online. The fact that both these compression formats have found broad decoder support from Mobile Hardware and Android OS respectively has motivated this change.

Netflix video transcoding optimization update

Netflix optimize their encoding to H.264 high

AVCHi-Mobile (H.264 High Profile) and VP9 Codecs

Essentially the difference between baseline, main and high profiles of H.264 encoding is increasing compression efficiency, with the requirement of greater decoding capability. This means that compression in high profile reduces bitrates for a given stream quality more efficiently, but decoding it requires greater processor power.

OTT Video Platforms such as Netflix encode their streams for delivery across multiple devices. There are multiple considerations when encoding for multiple-device streaming delivery:

  • User internet bandwidth – The stream should be supported across the widest network bandwidth available. Encoding for low bitrate streaming is critical for users on low bandwidth internet connections, for example users who might be streaming on mobile internet connections.
  • Processor capability – Devices such as OTT Television and Desktops have much more processing power than mobiles. Mobiles have much lower decode capabilities, because of battery considerations and because low-screen size means that streaming is already optimized for low resolution for mobile. However increasingly decode capabilities are increasing in mobile devices, and increasing demand on low-bandwidth connections requires this increased decode capability for more effective video encoding.
  • Cost considerations – Streaming at high bitrates naturally entails higher costs for video content broadcasters. There is a trade-off there between video quality and cost. Video delivery providers therefore provide the optimal resolution for a comfortable experience.

Netflix’s latest update prioritizes video quality for low bandwidth internet connections. Prior to the update Netflix used AVCMain (H.264/AVC) profile for almost all video, and HEVC for videos in Ultra HD resolution. The two new compression formats that have been introduced are: AVCHi – Mobile and VP9-Mobile.

Optimizations

In terms of optimizing video encoding, Netflix have made the following changes:

  • Increasing time period between random access points – This makes encoding more efficient, while increasing the time between I-frames, making seeking videos more granular.
  • Allowing more B-frames, and better motion prediction, to reduce the number of heavy I-frames

Per-chunk Optimization

The feature of per-chunk optimization allows encoding at different average bandwidths for different chunks of video. This is in place of an average bitrate for the entire video. This feature ensures that motion-heavy chunks are encoded at high bitrate as compared to low-motion chunks, ensuring smooth quality of video throughout the streaming process.

Conclusion

Netflix have updated to H.264 High Profile and VP9 codecs largely to maximize their reach to more number of users for reliable streaming. This update has come shortly after announcement of download feature for their mobile app. Additional optimization related to placement of I-frames and optimization of motion signify that the company is leveraging improving decoder capabilities for more efficient encoding. The resulting encoding efficiency improvements signify that AVCHi-Mobile encodes at 15-19% lower bitrates than similar quality AVCMain, while VP9 offers the same quality at 35% lower bitrate. The resulting improved quality for lower bitrate means a better experience for Netflix users.

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