Real-time MPEG Capture FAQ
The following Frequently Asked Questions and Answers are mainly for
Capturing Full D1 Standard-Definition MPEG Video (max. 720X576-Pixel PAL, 720X480-Pixel
NTSC) on PCs:
1.
What Is
“Realtime Hardware-Compression MPEG Video Capture Device”?
Video capture card or
box, such as Inventa MPEGIO2 or USBOSDM2, that use dedicated
hardware chip on-board to compress incoming video and audio into MPEG format in
real-time, without invoking any software on host PC to do compression. Since in
real-time compression of live video signal data, dedicated compression chip can
be made far superior in performance and efficiency than generic CPUs on the host
PC or on the PCB and will not be adversely influenced by the Generic CPU's other activities, this
leads to many un-challengeable advantages to
compress combined video and audio in real-time.
2.
Why Use
Hardware MPEG Encoding?
(1).Encoded
video is guaranteed to be smooth at playback, while capture cards using PC host
based software to compress video cannot achieve this, in particular when video
has camera panning and zooming contents
(2).Audio-Video
can be guaranteed to be synchronized in the captured video file, regardless the
sound card situation in the host PC, while software compression based capture
cards rely heavily on PC’s sound card to sync audio and video
(3).Minimum
host PC resources (CPU, Memory) are used for video encoding, even
when multiple-cards / multiple-channels are capturing and encoding video, while
software compression based capture devices consume large amount of host PC
resources, even on single channel encoding.
(4).Video
capture and compression will not be affected by other activities on the host
PC, while software compression based capture is always badly influenced by
other software running on the host PC.
3.
Are All
Hardware-Compression MPEG Capture Devices Create Same Quality Video?
Not at all, some have
proven to create extremely poor quality video and have constant audio-video
out-of-sync problem.
4. Why
Encode MPEG2 Program-Stream Video?
(1).Required for DVD(& SVCD)
Movie Disk Creation
(2).Easiest playback across Multiple
Platforms: decoders on all computers and non-computers can be easily found,
most time free or with minimum cost
In comparison, MPEG2 Transport-Stream Video, which Inventa MPEGIO2 and MPEGIO hardware also support, is mainly useful in Television Broadcasting environment and can be more efficient on video streaming, but has disadvantages like in-compatible with DVD/SVCD creation, difficult to find playback software, etc.
Video quality is better, smoother and perfect A/V sync can be achieved,
due to highly optimised circuit logic.
(1). High-Quality MPEG video output to external TV/VCR devices in addition to PC screen.
(2). Low PC Resources needed, this is particularly important in applications such as Multi-Channel Video-on-Demand Server etc, where multiple MPEG video streams needed to be decoded and streamed out simultaneously.
(3). No Software Codec (filters, decoders etc.) required on playback computers.
Advantages:
(1)
When encoding bit rate is lower than 2~3 Mbps, hardware-compressed MPEG4 can achieve better video quality than MPEG2.
(2) Lowest bit rate encoding is
normally lower than MPEG2.
Disadvantages:
(1) Each hardware MPEG4 encoder will
create different format of video, thus making playback
difficult. No universal MPEG4 playback mechanism exists
(2) MPEG4 video cannot be used to create DVD/SVCD Movie Disk.
(3)
MPEG4 video is difficult to be edited: finding editing software to
recognize/accept a hardware-compressed MPEG4 video and to edit then save it in
original format is difficult.
Not on all hardware-compression MPEG encoding devices, and normally cannot be achieved on software-compression MPEG2/4 video capture cards.
9. What Advantages Hardware-Compressed MPEG1 Video Has over MPEG2 and MPEG4?
Advantages: (1) Universal playback on all software/hardware video players and its decoding capability is natively built-in to MS Windows, Apple Mac etc. operating systems which means the MPEG1 video can play under a freshly installed Windows or
Mac PC without any extra Codec software thus avoiding complicated video codec installation and mutual-interference headaches.
(2) Can burn VCD movie disks to be played on stand-alone DVD players.
Disadvantages:
(1) Lower frame size (max. 352X288/320X240-Pixels) so lower quality compared with MPEG2/MPEG4 which can have D1(720x576/720X480) or higher frame sizes.
(2) When encoded at the same very low bit rates video quality is usually not as good as MPEG4 video encoded at the same low bit rate.