Digital Video - step by step proctical workshop.

17/10/00

 

Presenters: Tadeusz Zubowicz and Tadeusz Matuszkiewicz

 

The workshop includes some information on:

- Video Standards.

- Standard 1394a (Firewire).

- What to do and how to archive Digital Video?

- Digital Video capture, editing and compression programs.

- Demonstration of how to capture, edit, compressing and record Digital Video.

Few words on Video formats.


Standard VHS resolution is about 352 x 288 at 25 frames/sec. This is also the resolution of VideoCD (which is an MPEG-1 file on a CD in a particular format).


A Standard TV broadcast is 625 vertical lines (interlaced).You can work out the horizontal resolution if you know the bandwidth of the TV broadcast, but ends up being just a bit better than standard VHS.


Digital Versatile Discs (DVDs) have a resolution of 720 x 576 (about 4 times that of VHS) on a PAL system. NTSC is 720 x 480. The movie format on DVD is MPEG-2.


MiniDV, which is the format the digital video cameras use, is also 720 x 576 (PAL).


Firewire or 1394a.


DV™ is a digital video format, supported by a consortium of over 50 companies. Firewire™ is a serial data transfer protocol and interconnection system, used (amongst other things) to transmit DV.

Firewire was originally developed by Apple Computer, Inc. In 1995, Firewire was standardized by the Institute of Electrical and Electronic Engineers as IEEE 1394-1995.




The Firewire terminates in a

"Gameboy" like connector,

manufactured by Molex.






The Firewire has two individually

shielded pairs for data, and two

extra wires for power.





Sony uses a 4 conductor cable for the connection to the DV camcorders and DVCRs. They are like the above mentioned setup, but without the power wires. They terminate in smaller, 4prong connectors. To connect a Sony DV camcorder or DVCR with a standard IEE1394 Firewire device or interface card, you need an adapter cable, 4prong on one side, 6 on the other. It simply connects the data lines while omitting the power connection.

According to the standard, the IEEE 1394 "wire" is good for 400 Megabits per second over 4.5 meters.


DIGITAL VIDEO.


We now have the DV movies, Firewire card, fast computer and ….

.... what can we do with it?


Here are some options.


  1. We could say we have digital documentation and keep on collecting it.



  1. We could record it onto a computer, multiple CDs etc for storing it on a digital media. To preserve the quality and storing data in an uncompressed format would require huge disks or lots of CDs. Why copy it onto the computer in the original format if it is already in a digital format on tape. All we need is reliability of tape and the reading device (camera).



  1. We could record the films on a computer, Edit it and Save on computer or multiple CDs in compressed format i.e. smaller size and lower quality than the original movie to save space. The original movie remains on the tape.



  1. We could edit the recorded material and transfer what’s needed onto another digital camera.




Option 3 – Digital Video Editing.


First you need to record raw material on the HDD. DV creates 3.6 to 3.7 Megabytes of data per second. One minute, 222 Megabytes. 10 Minutes: 2.2 Gigabytes. A 90 minute, feature-length movie would fill 20 Gigabytes of hard drive space in final edited form. Also keep in mind that currently shipping Firewire solutions (or rather the drivers that come with them) don't allow to "Print to DV" from the Premiere timeline. Allow sufficient space for a target file for the "Make Movie" process. This is likely to change with future drivers, changes to the operating system or the editing application.


Quality of the software will determine what control you have over recording functions. Software can control the camera. The better the software, the better the control of your camera.

You may be able to specify exact timing FROM – TO for recording or you may need to operate the camera through PLAY – RECORD buttons inside the software.


Then you will need and need to know how to use a Video Editing software to produce a movie. You can mix video, sound, introduce effects etc.


Finally, the movie needs to be compressed to reduce its size and hopefully not reducing the movie quality completely.


Some software may allow for rerecording final movie on the DV Camera, but it would need to be in an uncompressed format.








Option 4 – Recording on the second DV Camera.


We could either try a direct 4pin to 4pin Firewire cable; connect 2 cameras; play on 1, record on the other.


or


We could connect 2 cameras with the existing 4pin to 6pin Firewire cables to a common Firewire card and again play on one camera, record on the second camera.





SOFTWARE SOLUTIONS.


MotoDV Express. (http://www.digitalorigin.com) also available from http://www.adds.com.au (A$245)

InterDV PE.

Software used for capturing movies from the DV Camera to computer was Digital Origin's INTRODV Personal Edition for Windows V1.1.

Full version of this software (available as a 30 free trial) is available for US$69 Internet download and removes all restrictions on the movie length as well as introduces a full range of subtitling and transition features.



Media Cleaner EZ. (http://www.terran.com)

Media Cleaner EZ is a multimedia compression software from Terran Computers which allows for compression and conversion of video and sound files into various formats especially for streaming over the Internet.




Adobe Premiere V5.5.

Adobe Premiere is a very powerful program for video editing and capture. Unfortunately it did not work with the Sony TRV-110E DV Camera as it was not able to capture the movies or control this type of camera. Adobe have a list of cameras which Premiere supports and these are listed at http://www.adobe.com/products/premiere/camcorders.html



Other, untested software solutions include:


DV Non-Linear Editor from DATA VIDEO ($299 at Harvey Norman)


Studio DV from PINNACLE ($349 at Harvel Norman)



 Jeszcze trochê o formatach Multimedia.

 

MPEG (http://www.pl.tomshardware.com/video/00q3/000913/index.html)

 

Dzieje MPEG zaczynaj¹ siê w roku 1987. MPEG oznacza Motion Pictures Expert Group, œwiatow¹ organizacjê, która projektuje niezale¿ne od producenta i platformy standardy kompresji wideo. Pierwsze dokonania zosta³y przedstawione w 1992 r. jako MPEG-1. By³a to podstawa dla mniej udanego europejskiego Video-CD. Z powodu ograniczonej rozdzielczoœci 352 x 288 pikseli, MPEG-1 nadaje siê tylko do u¿ytku domowego, a mo¿liwa do osi¹gniêcia jakoœæ wideo w odniesieniu do przep³ywnoœci danych (data rate) jest doœæ niska z dzisiejszego punktu widzenia. Wprowadzony w 1995 r. MPEG-2 jest g³ównie oparty na MPEG-1. Wy¿sza rozdzielczoœæ, wynosz¹ca maksymalnie 720 x 576 pikseli, to znaczna poprawa, pozwalaj¹ca na uzyskanie du¿o lepszej jakoœci wideo. Najnowszy format to MPEG-4, zaprezentowany przez grupê MPEG ca³kiem niedawno, w grudniu 1999 r.



MPEG-4 zawiera kilka wa¿nych ulepszeñ w porównaniu ze starszymi i uznanymi technologiami kompresji wideo, jak MPEG-1 i MPEG-2:

 

-            niezale¿ne kodowanie zdjêæ i obrazu

-            podwy¿szona wydajnoœæ kodowania, wydajniejsza kompresja zdjêæ, obrazu i tekstur

-           du¿e mo¿liwoœci wyboru rozdzielczoœci

-            skalowalna z³o¿onoœæ

-            rozszerzona korekcja b³êdów

-            zwiêkszona elastycznoœæ kodowania obiektowego

-           ma³e opóŸnienie bufora

-            globalna kompensacja ruchu (GMC)

-           zale¿na od zawartoœci skalowalnoœæ tekstur



Podobnie jak MPEG-2, MPEG-4 równie¿ sk³ada siê z ró¿nych profili. To pozwala na przystosowywanie strumienia audio/wideo do w³aœciwej aplikacji. MPEG-4 bierze pod uwage wyj¹tkowe wymagania dziedzin: komputerowej, telekomunikacyjnej i telewizyjnej. Koduje nie tylko prostok¹tne piksele, lecz równie¿ poszczególne obiekty sceny. Oto ma³y przyk³ad: samochód przeje¿d¿aj¹cy przed charakterystycznym t³em, które prawie siê nie zmienia. Podczas gdy obraz kodowany jest w wiele prostok¹tnych czêœci, samochód mo¿e zostaæ oddzielony jako obiekt i potraktowany jako sprite na niezmiennym tle.



MPEG 1 was the first MPEG standard defining the compression format for real-time audio and video. The video resolution is typically 352 x 240 or 352 x 288, although higher resolutions are supported. The maximum bitrate is about 1.5 Mbps. MPEG 1 is used for the Video CD format.

MPEG 2 extends the MPEG 1 standard to cover a wider range of applications. Higher video resolutions are supported to allow for HDTV applications, both progressive and interlaced video are supported. MPEG 2 is used for the DVD - Video and SVCD formats, and also forms the basis for digital SDTV and HDTV.

MPEG 3 was originally targeted for HDTV applications. This was incorporated into MPEG 2, so there is no MPEG 3 standard.

MPEG 4 uses an object-based approach, where scenes are modeled as compositions of objects, both natural and synthetic, with which the user may interact. Visual objects in a scene are described mathematically and given a position in a two- or three-dimensional space. Similarly, audio objects are placed in a sound space. Thus, the video or audio object need only be defined once; the viewer can change his viewing position, and the calculations to update the audio and video are done locally. Classical "rectangular" video, as from a camera, is one of the visual objects defined in the standard. In addition, there is the ability to map images onto computer-generated shapes, and a text-to-speech interface.

MPEG 7 standardizes the description of multimedia material (referred to as metadata), such as still pictures, audio, and video, regardless if locally stored, in a remote database, or broadcast. Examples are finding a scene in a movie, finding a song in a database, or selecting a broadcast channel. The searcher for an image can use a sketch or a general description. Music can be found using a "query by humming" format.

DV - IEC 61834 Defines the DV (originally the "Blue Book") standard, Data structure for DV-based audio, data and compressed video at 25 and 50 Mbps.

Digital 8 compresses video using standard DV compression, but records it in a manner that allows it to use standard Hi-8 tape. The result is a DV "box" that can also play standard Hi-8 and 8 mm tapes. On playback, analog tapes are converted to a 25 Mbps compressed signal available via the i-Link digital output interface. Playback from analog tapes has limited video quality. New recordings are digital and identical in performance to DV; audio specs and other data also same.

DTV Short for digital television, including SDTV, EDTV, and HDTV.

DVD – Video DVDs that contain about two hours of digital audio, video, and data. The video is compressed and stored using MPEG 2. The audio is either linear PCM or Dolby Digital compressed audio. DTS compressed audio may also be used as an option.

Linear PCM audio can be sampled at 48 or 96 kHz, 16, 20, or 24 bits per sample, and 1 to 8 channels. The maximum bitrate is 6.144 Mbps, which limits sample rates and bit sizes in some cases. For Dolby Digital audio, the bitrate is 64 to 448 kbps, with 384 kbps being the normal rate for 5.1 channels and 192 kbps being the normal rate for stereo. The channel combinations are (front/surround): 1/0, 1+1/0 (dual mono), 2/0, 3/0, 2/1, 3/1, 2/2, and 3/2. The LFE channel (0.1) is optional with all 8 combinations. For DTS audio, the bitrate is 64 to 1,536 kbps. The channel combinations are (front/surround): 1/0, 2/0, 3/0, 2/1, 2/2, 3/2. The LFE channel (0.1) is optional with all 6 combinations.

Information based on http://www.dvcentral.org and (http://www.video-demystified.com/)