 |
Zakładka z wyszukiwarką danych komponentów |
|
|
Zakładka z wyszukiwarką danych komponentów |
|
ADV612BST Arkusz danych(PDF) 4 Page - Analog Devices |
|
||||||||||||||||||||||||||||||
ADV612BST Arkusz danych(HTML) 4 Page - Analog Devices |
|
|
4 / 46 page  ADV611/ADV612 –4– REV. 0 INTERNAL ARCHITECTURE The ADV611/ADV612 is composed of eight blocks. Three of these blocks are interface blocks and five are processing blocks. The interface blocks are the Digital Video I/O Port, the Host I/O Port and the external DRAM manager. The processing blocks are the Wavelet Kernel, the On-Chip Transform Buffer, the Programmable Quantizer, the Run Length Coder and the Huffman Coder. Digital Video I/O Port Provides a real-time uncompressed video interface to support a broad range of component digital video formats, including “D1.” Host I/O Port and FIFO Carries control, status, and compressed video to and from the host processor. A 512 position by 32-bit FIFO buffers the com- pressed video stream between the host and the Huffman Coder. Hardware Field Rate Reduction In CCTV applications it is often desirable to reduce the field rate to achieve the highest possible compression. The ADV611/ ADV612 have special hardware to permit this function. It is possible to set a register on the ADV611/ADV612 during en- code mode that will automatically reduce the field rate. This is a 5-bit register that allows up to 31 fields to be “skipped.” Stall Mode It is possible to stall or halt the ADV611/ADV612 at any time during Encode Mode. This allows the user to feed uncompressed video data to these parts and to stop indefinitely between fields or even between pixels. This feature is useful when compressing video that is not coming into the ADV611/ADV612 at sustained VCLK rates. Stall Mode is enabled by asserting the Stall pin at any time during encode. Stall mode is enabled on the next clock cycle after the pin is asserted. Field Size Reporting The ADV611/ADV612 have a read-only register that allows the user to read the field size of the most recently compressed field. This feature is useful in the feedback loop of a precise bit rate controller. The data is valid after LCODE (unless an entire compressed field resides in the internal FIFO). DRAM Manager Performs all tasks related to writing, reading and refreshing the external DRAM. The external host buffer DRAM is used for reordering and buffering quantizer input and output values. Wavelet Kernel (Filters, Decimator, and Interpolator) Gathers statistics on a per-field basis and includes a block of filters, interpolators and decimators. The kernel calculates for- ward and backward bi-orthogonal, two-dimensional, separable wavelet transforms on horizontal scanned video data. This block uses the internal transform buffer when performing wavelet transforms calculated on an entire image’s data and so elimi- nates any need for extremely fast external memories in an ADV611/ADV612-based design. On-Chip Transform Buffer Provides an internal set of SRAM for use by the wavelet trans- form kernel. Its function is to provide enough delay line storage to support calculation of separable two dimensional wavelet transforms for horizontally scanned images. Programmable Quantizer Quantizes wavelet coefficients. Quantize controls are calculated by the external DSP or host processor during encode operations and de-quantize controls are extracted from the compressed bitstream during decode. Each quantizer Bin Width is com- puted by the BW calculator software to maintain a constant compressed bit rate or constant quality bit rate. A Bin Width is a per-block parameter the quantizer uses when determining the number of bits to allocate to each block (subband). Quality Box The quality box is defined using the Video Area Registers that are described in the Registers Descriptions section. The back- ground contrast is controlled using Background Contrast Regis- ters that are defined later in this document. It is possible to control both parameters on a per-field basis during Encode Mode. This enables the quality box to either move slowly across the image or to instantaneously jump from one location to the next. Run Length Coder Performs run length coding on zero data and models nonzero data, encoding or decoding for more efficient Huffman coding. This data coding is optimized across the subbands and varies depending on the block being coded. Huffman Coder Performs Huffman coder and decoder functions on quantized run-length coded coefficient values. The Huffman coder/de- coder uses three ROM-coded Huffman tables that provide ex- cellent performance for wavelet transformed video. Field Truncation It is possible to set a hard upper limit to the field size of each field during Encode Mode. The Huffman Coder is able to de- tect if the field size exceeds a preset threshold and then causes the remaining Mallat block data to be zeroed out, therefore, truncating the field’s data. The bitstream is truncated in such a way that all end-of-field markers are inserted. This means that the compressed bitstream can still be decompressed by any hardware or software ADV6xx decoder. The only penalty is the loss of Mallat blocks which, depending on how many are lost, will degrade the image quality of the truncated field. GENERAL THEORY OF OPERATION The ADV611/ADV612 processor’s compression algorithm is based on the bi-orthogonal (7, 9) wavelet transform, and imple- ments field independent subband coding. Subband coders trans- form two-dimensional spatial video data into spatial frequency filtered subbands. The quantization and entropy encoding pro- cesses provide the ADV611/ADV612’s data compression. The wavelet theory, on which the ADV611/ADV612 is based, is a new mathematical apparatus first explicitly introduced by Morlet and Grossman in their works on geophysics during the mid 80s. This theory became very popular in theoretical physics and applied math. The late 80s and 90s have seen a dramatic growth in wavelet applications such as signal and image process- ing. For more on wavelet theory by Morlet and Grossman, see Decomposition of Hardy Functions into Square Integrable Wavelets of Constant Shape (journal citation listed in References section). |
Podobny numer części - ADV612BST |
|
Podobny opis - ADV612BST |
|
|
Link URL |
| Polityka prywatności |
| ALLDATASHEET.PL |
| Czy Alldatasheet okazała się pomocna? [ DONATE ] |
O Alldatasheet | Reklama | Kontakt | Polityka prywatności | Linki | Lista producentów All Rights Reserved©Alldatasheet.com |
| Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
|
Family Site : ic2ic.com |
icmetro.com |
Polish ▼
English
Chinese
German
Japanese
Russian
Korean
Spanish
French
Italian
Portuguese
Polish
Vietnamese
Indian
Mexican
British
New Zealand
