1. Technical Field
The present invention relates to encoding/transcoding systems used to process video using High Efficiency Video Coding (HEVC or H-265). More particularly, the present system relates to the use of legacy encoding infrastructures for processing MPEG-4 (also referred to as Advanced Video Coding (AVC) or H-264), MPEG-2 or other type video signals to also enable optimal video quality when encoding in HEVC format.
2. Related Art
State of the art video quality is achieved today by performing complex multi-pass video encoding using the same codec technology for each pass, and incorporating multiple stages in each pass for collecting key video statistics that will be used by the final pass encoder, which in turn applies optimal bit rate allocation on a frame-basis.
While multi-pass encoding achieves optimal video quality, the complexity of performing multiple times the same encoding in real-time is not always possible due to performance limitations of the specific hardware device used for encoding.
Newer video codecs like High Efficiency Video Coding (HEVC) are extremely complex compared to MPEG-4 or MPEG-2. This implies that even though it is feasible to design systems that can handle multipass encoding for MPEG-2 and MPEG-4, designing systems that can perform multi-pass encoding of a newly introduced codec HEVC is a challenge and requires extremely powerful systems that are not currently economically feasible and competitive for all applications.
Embodiments of the invention propose to go beyond the conventional multi-pass encoding that is performed today on many real-time video encoders with similar complexity. Instead of trying to achieve multiple times the same encoding for newly introduced video codecs that are often too complex to meet real-time, embodiments of the present invention use a first pass encoder that is less complex, and thus easier to perform in real-time.
As one example, a system of the present invention includes a first pass encoder that is an H-264 encoder followed by a second pass HEVC encoder. The second pass HEVC encoder then performs more complex encoding that is not provided in the H-264 encoder.
Embodiments of the present invention make it possible to perform real-time multi-pass encoding for new and very complex codecs like HEVC by using less complex video codecs, such as an MPEG-2 or an MPEG-4 encoder, along an encoding pipeline. Thus, embodiments of the invention provide a design for a multi-pass encoder that can run real-time under the constraints of a specific appliance, via the use of these heterogeneous video codecs,
Embodiments of the invention allow for a faster development cycle of a multi-pass encoder for a newly introduced codec by reusing the infrastructure and multi-pass design of an established video encoder already dealing with older technology. Heterogeneous multi-pass video encoding can benefit video quality of both the new video codec and the old codec.
Embodiments of the invention do not limit to a less-complex first pass encoding followed by a more-complex second pass encoding. In an alternative embodiment, the less-complex encoding can be performed in the second pass after a more complex first pass. As an example, an MPEG-4 encoder can follow a first pass HEVC encoder.
Another aspect of the present invention considers that in the design for a multi format encoder, it will be expensive to have many multi-pass systems. Accordingly, in one embodiment a cost effective system is provided to have one or multiple common preliminary passes for all output formats, where the last pass will be different and will be based on the desired final output format.
Further details of the present invention are explained with the help of the attached drawings in which:
In
The pass 1 module 106 includes a multi frame buffer for the H-264 encoding steps. As shown, the statistics generated in the pass 1 module 106 can also be provided as statistical inputs to the HEVC encoder 110, What the HEVC encoder gets is statistics information extracted from the H-264 1st pass, which helps the H-264 second pass, as well as now the HEVC which also constitutes a second pass. The HEVC encoder 110 then can receive the same uncompressed video as the H-264 encoder 100 and use the statistical data from the conventional H-264 encoder 100 to provided improved encoded high video quality HEVC output.
The system shown in
Embodiments of the invention are not limited to a less-complex first pass encoding followed by a more-complex second pass encoding. In an alternative embodiment to that shown in
In a further alternative embodiment a cost effective system can be provided to have a common preliminary pass/passes fir all output formats, where the last pass will be different and will be based on the desired final output format. By having common passes, different multi pass systems can be made less expensive. Such a system can include the components as shown in
Although the present invention has been described above with particularity, this was merely to teach one of ordinary skill in the art how to make and use the invention. Ma additional modifications will fall within the scope of the invention as that scope is defined by the following claims.
This Application claims priority under 35 U.S.C. §119(e) from earlier filed U.S. Provisional Application Ser. No. 61/871,958 filed on Aug. 30, 2013 and incorporated herein by reference in its entirety.
Number | Date | Country | |
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61871958 | Aug 2013 | US |