Flexible Transport of 3-D Videos
Over Networks
Ahmed Hamza
Network Systems Lab
Simon Fraser University
July 15, 2013
Introduction
State of the Art
3D Video Representation
3D Video Coding
Transport Protocols
P2P Streaming
Adaptive 3D Video ...
Introduction
State of the Art
3D Video Representation
3D Video Coding
Transport Protocols
P2P Streaming
Adaptive 3D Video ...
Introduction
In the near term, popular 3-D media will most likely be in the
form of stereoscopic and multi-view video.
Transmission of ...
Platform for 3D Media Transport
IPTV
multimedia services delivered over IP-based managed
networks that provide the required level of quality of
service (Q...
The DVB channel is constrained by the physical channel
bandwidth to allow transmitting multi-view video (MVV).
The IP plat...
Introduction
State of the Art
3D Video Representation
3D Video Coding
Transport Protocols
P2P Streaming
Adaptive 3D Video ...
The most simple 3D video data representation
Each of the two captured views is presented to one of
the eyes
Can be multipl...
Multiplexing Stereo Video
Time Multiplexing
(double the frame rate)
Spatial Multiplexing
(half the resolution)
2D video signal along with geometry information of the scene
Video Plus Depth
texture
depth map
Multi-view Plus Depth (MVD)
Cam-0Cam-3Cam-6
Example
3D Image Warping
Ismaël Daribo and Hideo Saito, “A Novel Inpainting-Based Layered Depth Video for 3DTV,” IEEE
Tran...
Layered Depth Video (LDV)
Main Layer
(central color view and depth map)
Enhancement Layer
(color and depth occlusions)
pro...
Introduction
State of the Art
3D Video Representation
3D Video Coding
Transport Protocols
P2P Streaming
Adaptive 3D Video ...
3-D video encoding depends on the transport option and raw
video format.
Simulcast encoding:
encode each view and/or depth...
Multi-view extension of H.264/AVC
Enables inter-view prediction
Prediction structure is simplified by restricting inter-
v...
Multi-view Video Coding (MVC)
Independently code views and depth maps
Dependent encoding is also possible
Exploit correlation between texture and depth ...
Introduction
State of the Art
3D Video Representation
3D Video Coding
Transport Protocols
P2P Streaming
Adaptive 3D Video ...
Transmission Control Protocol (TCP)
may not be suitable for streaming live video with a strict
end-to-end delay constraint...
Datagram congestion control protocol (DCCP)
implements bidirectional unicast connections
both data and acknowledgements ca...
Introduction
State of the Art
3D Video Representation
3D Video Coding
Transport Protocols
P2P Streaming
Adaptive 3D Video ...
Traditional client-server unicast streaming model is not
scalable by nature.
Advantage of P2P solutions
scalable media dis...
Efficient for delivering content from the server that is at
the top of the tree to peers that are connected to each
other ...
Tree-Based Approach
Data are distributed over an unstructured network in
which each peer can connect to multiple peers.
Increased connectivity...
Introduction
State of the Art
3D Video Representation
3D Video Coding
Transport Protocols
P2P Streaming
Adaptive 3D Video ...
A mechanism should exist to estimate the network
conditions so as to adapt the video rate accordingly, in
order to optimiz...
DCCP + TCP-friendly rate control (TFRC)
TFRC rate calculated by DCCP can be utilized by the sender
to estimate the availab...
Adapting video rate to available bandwidth depends on
the encoding characteristics of the views.
One or more views can be ...
The behavior of the human visual system is another
paradigm for QoE-aware rate adaptation.
Exploit the suppression theory
...
Asymmetry can be achieved by scaling the quality in
one of the views (secondary view)
in spatial, signal-to-noise ratio (S...
Just Noticeable Distortion for
Asymmetric Stereo Coding
Video Sequence Threshold PSNR (dB)
Parallax Barrier Polarized Proj...
Asymmetric Coding at a Fixed Rate Using MVC
Spatial asymmetry
using additional down-sampling steps in the encoding
process...
Alternating views are coded at high and low quality.
Inter-view dependencies should be carefully
constructed (predict only...
Asymmetric MVC Coding
Asymmetric MVC Coding
Scalable Asymmetric Coding Using SVC
It is possible to obtain spatial and/or quality scalable right
and left views if they...
Scalable Video Coding (SVC)
Can be done in two ways:
encode both views using SVC
base layer of each view is encoded with a quality ~32 dB
enhancement ...
Asymmetric Encoding
for Stereoscopic 3D Video
Introduction
State of the Art
3D Video Representation
3D Video Coding
Transport Protocols
P2P Streaming
Adaptive 3D Video ...
Straightforward approach:
extend the concept of asymmetric coding to MVV streaming (for
relatively small number of views)
...
Discarding one view entirely and falling back to 2D video is
not a good choice.
switching from 3D to 2D results in signifi...
Subjective tests to evaluate the performance of scaling
methods in terms of delivered QoE under different
network conditio...
Recommended adaptation policy:
QoE-based Adaptation Policy
State Method
1 All views transmitted at max quality
2 Asymmetri...
Introduce quality difference between adjacent views.
View that are either transmitted or not are encoded with
H.264/AVC fo...
a) High link capacity (4.5 Mbps)
b) Low link capacity (3.3 Mbps)
c) Very Low capacity (2.1 Mbps)
MVV Adaptation Example
Introduction
State of the Art
3D Video Representation
3D Video Coding
Transport Protocols
P2P Streaming
Adaptive 3D Video ...
European project
Peer-assisted multi-view video broadcast
Scalable architecture that utilizes the upload capacity of
peers...
Three modules:
3-D content server
master peers
3-D media streaming server
Peers that use both DVB
and IP channels synchron...
DIOMEDES Client
Adopts a mesh-based topology
Flat connections with no hierarchy
Adopts a divide-and-conquer approach and splits
content in...
Chunk exchange is managed by two governing policies:
Rarest-first chunk scheduling
Determines the chunks to be requested
F...
Chunk Mapping
Variable-size layered chunks
All chunks are self-decodable
Each chunk contains multiple GoPs
Adaptive video ...
P2P engine determines when to perform adaptation (discard/add a
stream).
Adaptation module determines which streams should...
Chunk Downloading
ready-to-play buffer
buffer duration is a variable that provides feedback on the
overall content retriev...
Chunk uploading
Request prioritization
Favor requests that belong to streams of high priority
Depth map streams should hav...
Full-resolution stereoscopic 3D video delivery
Full resolution source video is encoded as an
enhancement layer to the base...
Other Use Cases
Head tracking system for multi-view video delivery
head tracking system coupled with a stereoscopic display
View pairs cha...
Digital TV platforms are not flexible to support multi-view
video (cannot provide sufficient bandwidth).
Three adaptive st...
Flexible Transport of 3-D Video Over Networks, Proceedings of the
IEEE, 2011
Peer-to-peer system design for adaptive 3D vi...
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Flexible Transport of 3D Videos over Networks

  1. 1. Flexible Transport of 3-D Videos Over Networks Ahmed Hamza Network Systems Lab Simon Fraser University July 15, 2013
  2. 2. Introduction State of the Art 3D Video Representation 3D Video Coding Transport Protocols P2P Streaming Adaptive 3D Video Streaming Stereo Video Multi-view Video Case Study: DIOMEDES Outline
  3. 3. Introduction State of the Art 3D Video Representation 3D Video Coding Transport Protocols P2P Streaming Adaptive 3D Video Streaming Stereo Video Multi-view Video Case Study: DIOMEDES Outline
  4. 4. Introduction
  5. 5. In the near term, popular 3-D media will most likely be in the form of stereoscopic and multi-view video. Transmission of 3-D media, via broadcast or on-demand, to end users with varying 3-D display terminals (e.g., TV, laptop, and mobile devices) and bandwidths is one of the biggest challenges to bring 3-D media to the home and mobile devices. Two main platforms for 3-D video delivery: digital television (DTV) platforms Internet Protocol (IP) platforms Introduction
  6. 6. Platform for 3D Media Transport
  7. 7. IPTV multimedia services delivered over IP-based managed networks that provide the required level of quality of service (QoS) and experience, security, interactivity, and reliability WebTV services offered over Internet connections that support best effort delivery with no QoS guarantees, making them accessible anytime, anywhere as opposed to IPTV IP-based Delivery Platforms
  8. 8. The DVB channel is constrained by the physical channel bandwidth to allow transmitting multi-view video (MVV). The IP platform is more flexible in terms of bandwidth but is not reliable. A more recent research direction is to consider a combination of DVB and IP platforms to deliver MVV to provide free-view TV/video experience. Hybrid DTV-IP Approach
  9. 9. Introduction State of the Art 3D Video Representation 3D Video Coding Transport Protocols P2P Streaming Adaptive 3D Video Streaming Stereo Video Multi-view Video Case Study: DIOMEDES Outline
  10. 10. The most simple 3D video data representation Each of the two captured views is presented to one of the eyes Can be multiplexed either spatially (passive) or temporally (active) Temporal multiplexing has the advantage of maintaining the full resolution of each view Disadvantage: hardware representation dependency (acquisition process is tailored to a specific type of displays, baseline distance between the two cameras is fixed) Stereoscopic Video
  11. 11. Multiplexing Stereo Video Time Multiplexing (double the frame rate) Spatial Multiplexing (half the resolution)
  12. 12. 2D video signal along with geometry information of the scene Video Plus Depth texture depth map
  13. 13. Multi-view Plus Depth (MVD) Cam-0Cam-3Cam-6
  14. 14. Example 3D Image Warping Ismaël Daribo and Hideo Saito, “A Novel Inpainting-Based Layered Depth Video for 3DTV,” IEEE Transactions on Broadcasting, vol. 57, no. 2, June 2011
  15. 15. Layered Depth Video (LDV) Main Layer (central color view and depth map) Enhancement Layer (color and depth occlusions) projected on central viewpoint
  16. 16. Introduction State of the Art 3D Video Representation 3D Video Coding Transport Protocols P2P Streaming Adaptive 3D Video Streaming Stereo Video Multi-view Video Case Study: DIOMEDES Outline
  17. 17. 3-D video encoding depends on the transport option and raw video format. Simulcast encoding: encode each view and/or depth map independently using a scalable or non-scalable monocular video codec enables streaming each view over separate channels clients can request as many views as their 3-D displays require Dependent encoding: encode views using MVC to decrease the overall bit rate by exploiting the inter-view redundancies a special inter-view prediction structure must be employed to enable view-scalable and view-selective adaptive streaming Three-Dimensional Video Coding
  18. 18. Multi-view extension of H.264/AVC Enables inter-view prediction Prediction structure is simplified by restricting inter- view prediction to anchor pictures only Large disparity or different camera calibration affects coding efficiency Reference MVC software (JMVC) temporal and view scalability Multi-view Video Coding (MVC)
  19. 19. Multi-view Video Coding (MVC)
  20. 20. Independently code views and depth maps Dependent encoding is also possible Exploit correlation between texture and depth map Examples: sharing the texture video MVs with the depth map utilizing inter-layer motion prediction tool in SVC Multi-view Plus Depth Coding
  21. 21. Introduction State of the Art 3D Video Representation 3D Video Coding Transport Protocols P2P Streaming Adaptive 3D Video Streaming Stereo Video Multi-view Video Case Study: DIOMEDES Outline
  22. 22. Transmission Control Protocol (TCP) may not be suitable for streaming live video with a strict end-to-end delay constraint lack of control on delay (retransmissions) rapidly changing transmission rate (congestion control) provides good performance when available network bandwidth is about twice the maximum video rate (few seconds pre-roll delay) Transport Protocols
  23. 23. Datagram congestion control protocol (DCCP) implements bidirectional unicast connections both data and acknowledgements can flow in both directions congestion-controlled, unreliable datagrams congestion control mechanism selected at connection startup outperforms TCP under congestion when a video streaming scenario is considered Transport Protocols
  24. 24. Introduction State of the Art 3D Video Representation 3D Video Coding Transport Protocols P2P Streaming Adaptive 3D Video Streaming Stereo Video Multi-view Video Case Study: DIOMEDES Outline
  25. 25. Traditional client-server unicast streaming model is not scalable by nature. Advantage of P2P solutions scalable media distribution (reduce the bandwidth requirement of the server by utilizing the network capacity of the clients/peers) P2P solutions use overlay networks (data are redirected to another peer by the application) P2P Streaming
  26. 26. Efficient for delivering content from the server that is at the top of the tree to peers that are connected to each other in parent–child fashion. Shortcomings: ungraceful peer exit leads its descendants to starvation replicating the content for feeding multiple trees leads to redundancy within the network Tree-Based Approach
  27. 27. Tree-Based Approach
  28. 28. Data are distributed over an unstructured network in which each peer can connect to multiple peers. Increased connectivity alleviates the problem of ungraceful peer exit. building multiple connections dynamically requires a certain amount of time (initiation interval) More suitable for applications that may tolerate some initiation interval. Example: BitTorrent Mesh-Based Approach
  29. 29. Introduction State of the Art 3D Video Representation 3D Video Coding Transport Protocols P2P Streaming Adaptive 3D Video Streaming Stereo Video Multi-view Video Case Study: DIOMEDES Outline
  30. 30. A mechanism should exist to estimate the network conditions so as to adapt the video rate accordingly, in order to optimize the received video quality. Estimation can be performed by requesting receiver buffer occupancy status (to prevent buffer underflow/overflow) combining receiver buffer status with bandwidth estimation Adaptive Streaming
  31. 31. DCCP + TCP-friendly rate control (TFRC) TFRC rate calculated by DCCP can be utilized by the sender to estimate the available network rate When the video is streamed over TCP, an average of the transmission rate can be used to determine the available network bandwidth Basic method in DASH Adaptive Streaming
  32. 32. Adapting video rate to available bandwidth depends on the encoding characteristics of the views. One or more views can be encoded multiple times with varying bit rates, sender can switch between these streams according to the network conditions Similar to HTTP live streaming Encoding views once with multiple layers using SVC and switching between these layers Real-time encoding with source rate control Difficult with MVV Video Rate Adaptation Methods
  33. 33. The behavior of the human visual system is another paradigm for QoE-aware rate adaptation. Exploit the suppression theory human visual system (HVS) tolerates lack of high- frequency components in one of the views One of the views may be presented at a lower quality without degrading the 3-D video perception. Asymmetric quality allocation Adaptive Stereoscopic Video Streaming
  34. 34. Asymmetry can be achieved by scaling the quality in one of the views (secondary view) in spatial, signal-to-noise ratio (SNR) or temporal dimensions Questions Which method should be used? What is the level of asymmetry before observers start noticing visible degradations? Just Noticeable Distortion for Asymmetric Stereo Coding
  35. 35. Just Noticeable Distortion for Asymmetric Stereo Coding Video Sequence Threshold PSNR (dB) Parallax Barrier Polarized Projector Adile 31.9 33.07 Iceberg 31.64 33.05 Flower Pot 31.19 33.2 Train Tunnel 31.74 32.88 Results show that the “just noticeable” threshold PSNR is 33 dB for the polarized projection display 31.5 dB for the parallax barrier display
  36. 36. Asymmetric Coding at a Fixed Rate Using MVC Spatial asymmetry using additional down-sampling steps in the encoding process Temporal asymmetry skipping frames skipping from secondary view SNR (quality) asymmetry straightforward compared to other types of asymmetry (encoding quality of a view depends on the quantization parameter used) Asymmetric Encoding for Adaptive Streaming
  37. 37. Alternating views are coded at high and low quality. Inter-view dependencies should be carefully constructed (predict only from high-quality views). Asymmetric MVC Coding
  38. 38. Asymmetric MVC Coding
  39. 39. Asymmetric MVC Coding
  40. 40. Scalable Asymmetric Coding Using SVC It is possible to obtain spatial and/or quality scalable right and left views if they are simulcast coded using the SVC standard. Two encoding options for achieving scalable asymmetric stereoscopic video bitstreams when simulcast coding is used: encoding both views using SVC encoding one view with SVC and the other with H.264/AVC Asymmetric Encoding for Adaptive Streaming
  41. 41. Scalable Video Coding (SVC)
  42. 42. Can be done in two ways: encode both views using SVC base layer of each view is encoded with a quality ~32 dB enhancement layers are encoded at the maximum quality according to channel capacity only one view (the first) is scalably encoded second view is encoded using non-scalable H.264/AVC When the available link capacity is high, the scalable coded view (with the enhancement layer) becomes the high-quality view. Asymmetric Encoding for Stereoscopic 3D Video
  43. 43. Asymmetric Encoding for Stereoscopic 3D Video
  44. 44. Introduction State of the Art 3D Video Representation 3D Video Coding Transport Protocols P2P Streaming Adaptive 3D Video Streaming Stereo Video Multi-view Video Case Study: DIOMEDES Outline
  45. 45. Straightforward approach: extend the concept of asymmetric coding to MVV streaming (for relatively small number of views) A more efficient (in terms of bandwidth consumption) and flexible (in terms of number of views) approach: streaming the MVD representation (includes view scalability) View-selective encoding and interactive streaming of multi- view video requires computer vision methods for real-time head/gaze tracking, can be used to limit the number of views transmitted Adaptive Multi-view Video Streaming
  46. 46. Discarding one view entirely and falling back to 2D video is not a good choice. switching from 3D to 2D results in significant viewing discomfort With multi-view video (MVV) format, view scaling is a possible option missing view(s) may be outside of the user’s field of view or can be replaced by an artificial view generated at the client side Challenge How to determine which view should be discarded for minimum degradation in perceived quality? View Scaling
  47. 47. Subjective tests to evaluate the performance of scaling methods in terms of delivered QoE under different network conditions. 5-view 3D display at 1920x1200 screen resolution 12 male and 4 female assessors (7 experts) QoE-based Adaptation Policy Description Symmetric Quality Scaling Asymmetric Quality Scaling View Scaling Method # 1 2 3 4 5 6 Detail SNR Spatial SNR Spatial 3c+3d 2c+2d
  48. 48. Recommended adaptation policy: QoE-based Adaptation Policy State Method 1 All views transmitted at max quality 2 Asymmetric SNR scaling of intermediate views 3 Keep only edge views (+ depth) and use DIBR
  49. 49. Introduce quality difference between adjacent views. View that are either transmitted or not are encoded with H.264/AVC for high coding efficiency. Views that may have different qualities to achieve asymmetry are encoded using SVC. Example: For a five-view display, can perform this efficiently using SVC for views 2 and 4. Adaptation-ready Encoding
  50. 50. a) High link capacity (4.5 Mbps) b) Low link capacity (3.3 Mbps) c) Very Low capacity (2.1 Mbps) MVV Adaptation Example
  51. 51. Introduction State of the Art 3D Video Representation 3D Video Coding Transport Protocols P2P Streaming Adaptive 3D Video Streaming Stereo Video Multi-view Video Case Study: DIOMEDES Outline
  52. 52. European project Peer-assisted multi-view video broadcast Scalable architecture that utilizes the upload capacity of peers to assist distribution of up to 200 views and associated 3-D audio Main Idea: DVB-T signal provides stereoscopic 3-D media as a baseline P2P distribution of remaining MVV views over IP to enable immersive free-view TV experience Case Study: Project DIOMEDES
  53. 53. Three modules: 3-D content server master peers 3-D media streaming server Peers that use both DVB and IP channels synchronize the received signals. DIOMEDES Architecture
  54. 54. DIOMEDES Client
  55. 55. Adopts a mesh-based topology Flat connections with no hierarchy Adopts a divide-and-conquer approach and splits content into equally sized chunks Peers are of two types: Seeders: have the whole content and upload chunks to other peers Leechers: have some missing chunks BitTorrent Protocol
  56. 56. Chunk exchange is managed by two governing policies: Rarest-first chunk scheduling Determines the chunks to be requested Favors chunks that least distributed Tit-for-Tat Determines which chunk requests are to be accepted Sort neighbours based on their level of contribution May deny requests from neighbours at lower ranks Optimistic unchoking BitTorrent Protocol
  57. 57. Chunk Mapping Variable-size layered chunks All chunks are self-decodable Each chunk contains multiple GoPs Adaptive video streaming in 3D video streaming, rate adaptation is not straightforward and may depend on external information such as the user’s field of view, the encoding scheme, and the display properties Modifications to BitTorrent for 3D Video Streaming
  58. 58. P2P engine determines when to perform adaptation (discard/add a stream). Adaptation module determines which streams should be affected first. Modifications to BitTorrent for 3D Video Streaming
  59. 59. Chunk Downloading ready-to-play buffer buffer duration is a variable that provides feedback on the overall content retrieval rate Modifications to BitTorrent for 3D Video Streaming
  60. 60. Chunk uploading Request prioritization Favor requests that belong to streams of high priority Depth map streams should have the highest priority because they are used to generate multiple views at the client side. Base and enhancement layers may be prioritized similar to the case of 2D video streaming Modifications to BitTorrent for 3D Video Streaming
  61. 61. Full-resolution stereoscopic 3D video delivery Full resolution source video is encoded as an enhancement layer to the base stream in a frame- compatible format that is transmitted over the DTV channel. The enhancement layer is transmitted to enable full resolution 3D video for users with Internet access Other Use Cases
  62. 62. Other Use Cases
  63. 63. Head tracking system for multi-view video delivery head tracking system coupled with a stereoscopic display View pairs change according to a user’s viewing position if the available link capacity is low, only required video streams are received, based on the feedback from the head tracking device increase efficiency of rapid view selection by using a sparse camera arrangement and transmitting corresponding depth maps Other Use Cases
  64. 64. Digital TV platforms are not flexible to support multi-view video (cannot provide sufficient bandwidth). Three adaptive streaming solutions: Asymmetric streaming Streaming using MVD Selective streaming Combining adaptation methods with adaptive P2P video streaming will provide a successful 3D video services solution in the near future. Streaming holographic 3D video over IP might be possible on the long term. Conclusions
  65. 65. Flexible Transport of 3-D Video Over Networks, Proceedings of the IEEE, 2011 Peer-to-peer system design for adaptive 3D video streaming, IEEE Communications Magazine, 2013 DIOMEDES: Content Aware and Adaptive Delivery of 3D Media over P2P/IP and DVB-T2, Networked & Electronic Media (NEM) Summit, 2011 Evaluation of Asymmetric Stereo Video Coding and Rate Scaling for Adaptive 3D Video Streaming, IEEE Transactions on Broadcasting, 2011 References
  66. 66. Thank You!

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