Universal Format Converter Implementation 142 nd SMPTE Technical Conference Jeff Harris Panasonic AVC American Laboratories, Inc. Westampton, NJ
More than implementing an interpolation engine.
Topics Filtering Time Code Code I/O System Delays Delays Frame/Field Processing Gen Lock Lock Audio Frame/Field Processing Audio Color Matrices Matrices Architecture Flexibility Architecture Flexibility
Filtering Time Code I/O Issues Delay Issues Frame/Field Processing Gen Lock Audio Color Matrices Architecture Flexibility
Lowpass Filtering Provides pre-filtering for interpolation engine Anti-aliasing for subsampling interpolation Frequency response shaping To provide softening of hard edges to reduce ringing To allow user selectable enhancement
Lowpass Filtering (cont.) Filter selection Calculated Scaling requirements of conversion Vertical chroma subsampling Zoom ratio User control Rolloff characteristics Enhancement
Lowpass Filtering (cont.) Design goals Support large number of filters to allow smooth zooming without detectable change in response characteristics. Tradeoffs Anti-aliasing Ringing Sharpness Ripple
Lowpass Filtering (cont.) Complications Interlaced formats Chroma subsampling
Lowpass Filtering (cont.) An approach A database of precalculated filter coefficients downloaded dynamically For interlaced, recognition of constraints on output bandwidth For 4:2:0p input, pre-interpolation of missing chroma samples to process as 4:2:2
Filtering Time Code I/O Issues Delay Issues Frame/Field Processing Gen Lock Audio Color Matrices Architecture Flexibility
Time Code Supports various sources Converts appropriately from input format to output format Complications Film modes Drop Frame Mixed 24/25 Hz applications
Time Code (cont.) HD Serial (LTC, VITC) SD Serial (VITC) HD Serial (LTC, VITC) SD Serial (VITC) External LTC External LTC
Time Code (cont.) Supports various sources Converts appropriately from input format to output format Complications Film modes Drop Frame Mixed 24/25 Hz applications
Time Code (cont.) H:M:S:FR 01:00:00:00 01:00:00:01 01:00:00:02 01:00:00:29 01:00:00:00 01:00:00:01 01:00:00:02 01:00:00:29
Time Code (cont.) Supports various sources Converts appropriately from input format to output format Complications Film modes Drop Frame Mixed 24/25 Hz applications
Time Code (cont.) 3:2 Conversion 24p 30i 24p 30i A B C D 01:00:00:00 01:00:00:01 01:00:00:02 01:00:00:03 01:00:00:00 01:00:00:00 01:00:00:01 01:00:00:01 01:00:00:02 01:00:00:02 01:00:00:03 01:00:00:03 01:00:00:04 01:00:00:04 F1 F2 F1 F2 F1 F2 F1 F1 F2 F1
Time Code Supports various sources Converts appropriately from input format to output format Complications Film modes Drop Frame Mixed 24/25 Hz applications
Time Code (cont.) Approach: provide lockable input and output time code generators Input TC INPUT TC GEN NDF TC Lock Decisions OUTPUT TC GEN DF or NDF TC DELAY Output TC
Time Code (cont.) Example: Slow PAL to NTSC 25 Hz TC 24 Hz TC 29.94 Hz NDF TC 29.94 Hz DF TC
Filtering Time Code I/O Issues Delay Issues Frame/Field Processing Gen Lock Audio Color Matrices Architecture Flexibility
I/O Supports SDI for HD formats at 1.5 Gb/s (SMPTE 292M) and SD at 270/360 Mb/s (SMPTE 259M/294M) 4:2:0p vs. 4:2:2 Autoformat Detection TRS Flexibility for future I/O standards
Filtering Time Code I/O Issues Delay Issues Frame/Field Processing Gen Lock Audio Color Matrices Architecture Flexibility
System Delays Generally unavoidable Must be understood and predictable Not necessarily fixed across 24 to 60 Hz range of frame rates Time Code Audio
Filtering Time Code I/O Issues Delay Issues Frame/Field Processing Gen Lock Audio Color Matrices Architecture Flexibility
Frame/Field Processing Provides frame rate conversion to modes that are more readily viewable Film to 3:2 or 2:2 (segmented frame or progressive) Provides frame reconstitution from a segmented frame or 3:2 interlaced source
Filtering Time Code I/O Issues Delay Issues Frame/Field Processing Gen Lock Audio Color Matrices Architecture Flexibility
Gen Lock Accepting synchronization signals from various sources input external bi-level or tri-level signal NTSC or PAL Blackburst signals
Gen Lock (cont.) General approach: provide ability to lock two timing signals that are each related to the reference. Allows use of Blackburst as reference.
Filtering Time Code I/O Issues Delay Issues Frame/Field Processing Gen Lock Audio Color Matrices Architecture Flexibility
Audio Compensate for video processing delays automatically. Provide user adjustable delay. Provide selection of embedded or external (AES) audio source.
Audio (cont.) Provide manual control of synchronizer Allows non-audio data that is in the audio stream to pass intact
Filtering Time Code I/O Issues Delay Issues Frame/Field Processing Gen Lock Audio Color Matrices Architecture Flexibility
Color Matrices Provide automatic matrix selection based upon conversion Provide manual matrix selection Approach allows easy adjustment of component gain.
Filtering Time Code I/O Issues Delay Issues Frame/Field Processing Gen Lock Audio Color Matrices Architecture Flexibility
Architecture Flexibility A balance of hardware and software Format and I/O characteristics implemented in software Allows adaptation to future digital video standards
More than implementing the interpolation engine.