Method and apparatus for decoding an enhanced video stream
Disclosed are herein are methods and systems for encoding and decoding enhanced video streams using a legacy and scalable video components. In one aspect, a method of encoding video data in a packetized elementary stream (PES), is disclosed. The method includes receiving a signal including frames of image data, wherein the frames include base layer and enhancement layer components; encoding the frames of image data to form video access units (AUs), wherein base layer AUs are formed for base layer components and enhancement layers AUs are formed for enhancement layer components, each AU including: an elementary stream header (ELSM) including image data metadata parameters associated with decoding and displaying the image data; a PES header including a presentation time stamp (PTS) and a PES packet length indicating the length of the PES header; one or more codestreams associated with a frame of the image data; adding a network abstraction layer (NAL) unit header defined by an enhancement layer video standard to each base layer AU, the NAL unit header being a constant value and length; and forming a modified PES header by increasing the PES packet length to include the length of the NAL unit header in it.
1. A method of packetized elementary stream (PES) encapsulation from elementary streams, the method comprising:
receiving a signal including frames of image data, wherein the frames include base layer and enhancement layer components;
encoding the frames of image data to form video access units (AUs) in elementary stream each base layer AUs is formed to correspond to at least one network abstraction layer (NAL) unit header conforming to a first video coding standard for base layer components, and each enhancement layer AUs is formed to correspond to at least one network abstraction layer (NAL) unit header conforming to a second video coding standard for enhancement layer components;
encapsulating the elementary streams in to a PES for transport, the encapsulating including:
identifying at least a portion of the base layer AUs in a first elementary stream and at least a portion of the enhancement layer AUs in a second elementary stream;
adding an additional NAL unit header conforming to the second video coding standard in to the first elementary stream, before the at least one NAL unit headers corresponding to the base layer AUs in the first elementary stream, such that the first elementary stream includes multiple NAL unit headers;
aligning a byte-stream start code in a PES header associated with the base layer AUs in the first elementary stream with the added NAL unit header;
in the PES header for the base layer AUs associated with the first elementary stream, incrementing a PES packet length, indicating the length of the PES payload following the byte-stream start code, by a number of bytes for the added NAL unit header.
2. The method of claim 1 , further comprising:
mapping the AUs into PES packets; and
ordering the PES packets to form a PES in a transport stream,
wherein the transport stream includes a base layer formed from base layer AUs and an enhancement layer formed from enhancement layer AUs.
3. The method of claim 1 , wherein a NAL unit header directly precedes each base layer AU.
4. The method of claim 1 , wherein each HEVC NAL unit header is configured to signal and carry each AVC AU.
5. The method of claim 4 , wherein each AVC AU includes at least one of: AU delimiter, SEI, SPS, PPS, and video slices.
6. The method of claim 1 , further comprising:
mapping the AUs into PES packets; and
ordering the PES packets to form a PES in a transport stream,
wherein the transport stream includes a base layer formed from base layer AUs and an enhancement layer formed from enhancement layer AUs,
wherein the transport stream includes at least two packet identifiers (PIDs) and a program map table (PMT), and
wherein the AVC base layer PES packets are carried in a first dedicated PID.
7. The method of claim 6 , wherein the PMT signals the base layer AVC with MPEG defined stream type of 0x1 B.
8. The method of claim 6 , wherein the HEVC enhancement layer is carried in a second dedicated PID.
9. A method of decoding video data in a packetized elementary stream (PES), the method comprising:
receiving a transport stream including:
the PES, wherein the PES includes frames on image data in video access units (AUs) including both base layer AUs associated with at least one respective packet identifier (PID) in a plurality of packet identifiers (PID)s and enhancement layer AUs associated with a respective packet identifier in the plurality of PIDs,
wherein base layer AUs formed in the PES from base layer components are formed based on a first coding technology and enhancement layer AUs formed in the PES from enhancement layer components are formed based on a second coding technology;
determining a PES packet length received for the base layer AUs associated with the first PID, the PES packet length indicating the length of the PES payload following a byte-stream start code, said PES including multiple NAL unit headers, wherein the PES packet length is incremented to include a number of bytes for a NAL unit header conforming to a second video coding technology added before one or more NAL unit headers for the base layer AUs associated with the first PID, the one or more NAL unit headers for the base layer AUs conforming to a first video coding technology;
if the decoder is compliant with the first coding technology, decoding the base layer AUs in accordance with a start code in the PES header aligned with the added NAL unit header and the received PES packet length for re-assembly of an elementary stream comprised of the base layer AUs based on the one or more NAL unit headers conforming to the first video coding technology; and
if the decoder is compliant with the second coding technology, decrementing the PES packet length field by the number of bytes of the added NAL unit header conforming to the second video coding technology for re-assembly of the elementary stream comprised of the baser layer and enhancement layer AUs.
10. The method of claim 9 , wherein the decoding is performed by a legacy decoder.
11. A method of decoding video data in a packetized elementary stream (PES), the method comprising:
receiving the PES, wherein the PES includes frames on image data in video access units (AUs) including both base layer AUs associated with at least one respective packet identifier (PID) in a plurality of packet identifiers (PID)s and enhancement layer AUs associated with a respective packet identifier in the plurality of PIDs and,
wherein base layer AUs are formed in the PES from base layer components based on a first coding technology and enhancement layer AUs are formed in the PES from enhancement layer components based on a second coding technology
determining a PES packet length received for the base layer AUs associated with the first PID, the PES packet length indicating the length of the PES payload following a byte-stream start code, said PES including multiple NAL unit headers, wherein the PES packet length is incremented to include a number of bytes for a NAL unit header conforming to a second video coding technology added before one or more NAL unit headers for the base layer AUs associated with the first PID, the one or more NAL unit headers for the base layer AUs conforming to a first video coding technology;
forming an original PES header by decreasing the PES packet length by the value that represents the added NAL unit header length;
removing the original PES header for each base layer AU;
removing the original PES header for each enhancement layer AU; and
decoding each base layer AU and each enhancement layer AU to form a signal including frames of image data, wherein the base layer AUs are Advanced Video Coding (AVC) video data and the NAL unit header is exclusively HEVC video data.
12. The method of claim 11 , further comprising:
receiving a signal indicating that the modified PES header will be decremented by the constant value.
13. A system configured to encode video data in a packetized elementary stream (PES), the system comprising:
a processor configured to
receive a signal including frames of image data, wherein the frames include base layer and enhancement layer components;
encode the frames of image data to form video access units (AUs) in elementary stream each base layer AUs is formed to correspond to at least one network abstraction layer (NAL) unit header conforming to a first video coding standard for base layer components, and each enhancement layer AUs is formed to correspond to at least one network abstraction layer (NAL) unit header conforming to a second video coding standard for enhancement layer components;
encapsulating the elementary streams in to a PES for transport, the encapsulating including:
identify at least a portion of the base layer AUs in a first elementary stream and at least a portion of the enhancement layer AUs in a second elementary stream;
add an additional NAL unit header conforming to the second video coding standard in to the first elementary stream before the at least one NAL unit headers corresponding to the base layer AUs in the first elementary stream, such that the first elementary stream includes multiple NAL unit headers;
align a byte-stream start code in a PES header associated with the base layer AUs in the first elementary stream with the added NAL unit header;
in the PES header for the base layer AUs associated with the first elementary stream, increment a PES packet length, indicating the length of the PES payload following the byte-stream start code, by a number of bytes for the added NAL unit header, and
executable instructions for controlling the processor.