2K Processor AJ-HDP2000

Transcription

1 Jan.31, K Processor AJ-HDP2000 Technical Overview Version 2.0 January 31, 2007 Professional AV Systems Business Unit Panasonic AVC Networks Company Panasonic Broadcast & Television Systems Company

2 1. Development Background In 1995 Panasonic introduced its first digital HD VTR, consisting of a standard definition D5 VTR that worked in combination with an external HD processor. Since those early days, D5-HD has evolved significantly. In 1997 the external HD processor was built into the VTR and many new functions added and thus created a new D5-HD model, the AJ-HD2700. Importantly, this was the first HD VTR to be fully capable of both 1080i and 720p native operation. To date we have sold more than 3,000 D5-HD VTRs worldwide (as of Sep. 2006), with more than 2,000 units within the U.S alone. Panasonic has demonstrated industry leadership with the D5-HD format, a de facto standard, largely due to D-5 s full bandwidth HD recording, superb picture quality, multi-format support, technical superiority, reliability and a cost-effective product solution. In 2000, Panasonic introduced the AJ-HD3700, a machine with 24 frame progressive recording capability. The AJ-HD3700 has very been very widely accepted in Hollywood and throughout the entire post production community. The universality and wide acceptance of the D5 platform has lead to the AJ-HD3700 becoming a de facto standard for HD mastering. With the support of the Hollywood studio and post community, Panasonic has provided continuous development of the AJ-HD3700 platform over the past 5 years. In recent years, the market has been moving toward higher resolution imaging including 2K (2048x1080), 4:4:4 sampling with a need for 12 bits per channel. To meet this new requirement, Panasonic will also support 1920x1080 and true 2K image recording at 4:4:4, with full 12bit sampling by means of a new processor, the AJ-HDP2000. The new processor is designed to work in conjunction with all AJ-HD3700 VTRs, providing current HD3700 customers with an up-grade path to 2K resolution and 4:4:4, 12bit sampling. Panasonic is thus committed to continuing technology development for the AJ-HD3700 platform in order to meet the growing needs of the production and post production mastering market. The new 2K Processor utilizes JPEG2000; J2K (ISO/IEC15444) compression which has also been adopted by DCI (Digital Cinema Imaging) group. Using J2K compression it is possible to record up to 2048 x 1080 with 4:4:4 resolution on existing AJ-HD3700H, AJ-HD3700A and AJ-HD3700B VTRs. A software upgrade is required for AJ-HD3700 VTRs delivered before September, 2007 This paper provides preliminary basic specifications of the 2K Processor and system diagram. Design work is ongoing so some specifications may change. Page 2 of 7

3 1.1. Specification (Tentative) General Specification Power Source: AC: 120 V ±10%, 50/60 Hz Power Consumption: Max. 75W Operating Temperature: 5 C to 40 C Operating Humidity: 10% to 80% (no condensation) Weight: Approx 10kg Dimensions (W x H x D): 424 x 87 x 470 mm (2RU size) Recording Video Signal: 2048x1080/23.98p, 24P XYZ / RGB 4:4:4 1920x1080/23.98p, 24P RGB 4:4:4 Video Recording Format: HD-D5 JPEG2000 Audio Recording Format: 48kHz/24bits, 8CH Recording Media: HD-D5 Tape Recording/Playback Time: AJ-D5C124L Approx. 155min. Digital Slow: 1 to +1 times normal speed Video Specification Sampling Frequency: Quantizing: Video Compression Format: Error Correction: Video Bit Rate: 4:4:4, MHz / 74.25Hz 12 bits JPEG2000 (ISO/IEC15444) Reed-Solomon product code 188Mbps Video Input Signal Dual Link SDI Input Video Output Signal Dual Link SDI Output: Single HD SDI Monitor Output BNC x 2, 75 ohm 1920x1080/23.98PsF, 24PsF 4:4:4 SMPTE372M/291M/292M/299M standard 2048x1080/23.98PsF, 24PsF XYZ 4:4:4 BNC x 4, 75 ohm 1920x1080/23.98PsF, 24PsF 4:4:4 SMPTE372M/291M/292M/299M standard 2048x1080/23.98PsF, 24PsF 4:4:4 SMPTE Ref Docs Under Development BNC x 1, 75 ohm (Super ON/OFF) 1920x1080/23.98PsF, 24PsF YPrPb 4:2:2 SMPTE292M standard (Video signal only w/o ANC data) Audio Specification Sampling Frequency: Quantizing: Audio Specification (VTR:HD-D5) 48 khz (sync video) 24 bits Page 3 of 7

4 Frequency Response: Dynamic Range: Distortion: Cross Talk: Wow & Flutter: Audio Input Signal Dual Link SDI Input (Embedded Audio) Audio Output Signal Dual Link SDI Output (Embedded Audio) TC Input Signal Dual Link SDI Input (Embedded LTC/VITC) TC Output Signal Dual Link SDI Output (Embedded LTC/VITC) Other Input and Output HD Reference Input: HD SYNC Output Serial Data Output (VTR HD_SDI) Serial Data Input (VTR HD_SDI) 20 Hz to 20 khz, ±0.5 db (reference level) More than 105 db (1 khz, emphasis off, A weighted) Less than 0.01% (1 khz, emphasis off, reference level) Less than 80 db (1 khz, between 2 channels) Below measurable limit BNC x 2, 75 ohm (Ach only) (Input using VCR AES & Analog Audio In is also possible.) SMPTE299M standard BNC x 4, 75 ohm (Ach only) (Outputs from the VCR AES & Analog Audio is also possible.) SMPTE299M standard BNC x 2, 75 ohm (Ach only) SMPTE291M standard BNC x 4, 75 ohm (Ach only) SMPTE291M standard BNC x 2 (loop-through x1), 75 ohm automatic termination HD(1920x1080/23.98PsF) tri-level sync, BNC x 1, 75 ohm HD(1920x1080/23.98PsF) tri-level sync, BNC x 1, 75 ohm 1920x1080/23.98PsF SMPTE291M/292M/299M compliance BNC x 1, 75 ohm 1920x1080/23.98PsF SMPTE291M/292M/299M compliance Page 4 of 7

5 1.2. 2K Processor and D5-HD System Diagram Page 5 of 7

6 1.3. JPEG2000 compression To make the best use of the D5-HD performance for 2k recording, a new compression scheme based on JPEG2000 has been developed. The following performance characteristics are necessary for compression of professional images for video tape recording. (1) Visually lossless picture quality including the process of duplicating tapes. (2) Constant bit rate control for linear editing of the video tape. (3) Error tolerance for reliable video tape operation and interchange. The digital payload calculated from the sample ratio between 1920/4:2:2 10bit and 2048/4:4:4 12bit is 1.6. In other words, it is necessary to compress 1.6 times higher to record 2048/4:4:4 12bit with D5-HD. On the other hand, especially for the progressive picture, JPEG2000 compression is almost twice as efficient as the compression scheme used previously for HD recording in D5 video tape recorders. Therefore, 2048/4:4:4, 12bit pictures can be compressed into the D5-HD bit rate without degradation of picture quality Visually lossless compression There are two main reasons for JPEG2000 s high compression efficiency. JPEG2000 uses the Wavelet transform instead of the more conventional DCT transform. As such the image isn t divided into small 8x8 blocks like DCT based compression. Therefore, block distortion is not present even when high compression ratios are used. However, the required high picture quality for 2k recording on D5 does not require a high compression level. The Wavelet transform can also improve the required picture quality at low compression ratios because the lengths of Wavelet bases are different according to the frequency. The length of higher frequency bases that describe details of the picture are shorter at lower compression ratios. In the compression process, distortions can occur in the neighborhood of picture edges. This is because the high frequency element of the edge is lost in the compression process. The distortion of the edge neighborhood doesn t diffuse widely because high frequency bases of the Wavelet transform are short. This fact contributes to visual quality improvement when compressing at low ratios such as when recording on a D5 video tape recorder. Secondarily, JPEG2000 adopts a very efficient entropy encoding method called MQ-coder. Using MQ-coder, almost theoretical limits are possible when using an advanced context modeling method. Video distortion does not occur in this entropy process, as entropy encoding is a reversible transparent process. This new technique requires a significant increase in the computational complexity that was solved by the advancement of semiconductor technology. MQ-coder entropy encoding contributes to a significant improvement in compression efficiency Constant bit rate control The data length of one frame should be fixed to guarantee the linear video tape editing capability. However, it is very difficult to control bit rates because the information requirement varies greatly depending on picture content. Therefore, D5-HD had adopted a method to predict data length by pre-encoding using eight different quantization schemes. Page 6 of 7

7 JPEG2000 has highly optimized bit rate control in the published standard. Exact bit rate can be controlled by bit-plane coding called EBCOT (Embedded Block Coding with Optimized Truncation). EBCOT decides the strategy of the bit distribution by truncation for every code-block. Only information on the LSB side is truncated because bit-plane coding is encoded from the MSB side. Therefore, the picture quality degradation is suppressed to the minimum even if the exact bit rate must be controlled Error tolerance Errors can occur in video tape recorders from various factors such as tape scratch, dropout, head clogging, etc. These errors are unpredictable and inevitable. These errors can be very serious when compression is used in the recording process. Because of the compression there is high risk that one error will spread widely and be more visible in the picture. Therefore, modern VTRs require improved error tolerance. Two typical techniques for error handling are: (1) Error correction (2) Error concealment Error correction is a process that completely corrects errors using Error Correction Code (ECC). Error concealment seeks to make any errors remaining after correction indiscernible. The AJ-HDP2000 2K Processor has an enhanced 3 rd ECC in addition to inner/outer ECC of D5-HD. Error correction ability has been strengthened so that it is possible to correct even if one track data disappears completely. JPEG2000 is composed by multi-resolution decomposition. Each sub-band has a different importance respectively. The difference of importance can be used for error concealment. An error which occurs in low priority data can be neglected instead of corrected. Moreover, JPEG2000 has a built-in method that prevents error propagation therefore the range of error propagation is limited. The error tolerance of 2K Processor is improved enough by this methodology. Conclusion: Panasonic has developed a new process for recording and playing of 2K, 2048x1080 4:4:4 12-bit images and 1920x1080 RGB HD images at up to 12-bit depth utilizing the existing AJ-HD3700 multi-format video tape recording system. The process incorporates JPEG2000 compression algorithm already standardized and widely accepted for digital cinema and other high-end image compression applications. This system provides a cost-effective and efficient method of recording, editing and archiving of 2K and 4:4:4 HDTV images on a commonly used video tape with all the inherent advantages of the modern video tape recorder. This new system is intended to operate in video tape applications using the same operational techniques in wide use for high definition and standard definition content creation and distribution. Page 7 of 7