Realtime MPEG Capture FAQ

 

The following Frequently Asked Questions and Answers are mainly for Capturing 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 MPEGIO or USBMPEG2-Box, that use dedicated hardware chip on-board to compress incoming video and audio into MPEG format in realtime, without invoking any software on host PC to do compression. Since in realtime compression of live video signal data, dedicated compression chip can be made far superior in performance and efficiency to generic CPUs on the host PC and not being adversely influenced by the Host PC's other activities, this leads to many un-challengeable advantages over using host based software to compress combined video and audio in realtime.

 

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 capture & 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

(3).High Quality Video Playback onto Analogue TV Screen through hardware MPEG2 decoder, such as MPEGIO.

In comparison, MPEG2 Transport-Stream Video, which Inventa MPEGIO and MPEGIOPro hardware also support, is mainly useful in Television Broadcasting environment, but has disadvantages like in-compatible with DVD/SVCD creation, difficult to find playback software, etc.

 

  1. What Advantages does ASIC Chip Set Compression have against other chipsets(DSP, FPGA, etc)?

Video quality is better, smoother and perfect A/V sync can be achieved, due to highly optimised circuit efficiency.

 

  1. What Are Benefits of Hardware MPEG Decoding?

(1). High-Quality MPEG video output to analogue TV

(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.

 

  1. Compared with MPEG2, what Advantages and Disadvantages MPEG4 Has?

Advantages:   (1) When encoding bit rate is lower than 2~3 Mbps, hardware-compressed MPEG4 can easily achieve better video quality than MPEG2

                        (2) Lowest bit rate encoding is normally lower than MPEG2

Disadvantages:

(1)   Each hardware MPEG4 encoder will create at least slightly different format of video, thus making playback difficult. No universal MPEG4 playback mechanism exists

(2)   MPEG4 video is in-compatible with DVD/SVCD Movie Disk format

 

  1. Is A/V Sync Always Guaranteed on Hardware-Compression MPEG Capture?

Not on all hardware-compression MPEG encoding devices, and normally cannot be achieved on software-compression MPEG2 video capture cards.

 

  1. Why Using VideoLan During MPEG Capture Is Better than Normal Time-Shifting?

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Using the free VideoLan vlc.exe software with realtime MPEG capture cards like MPEGIO, allows side-by-side viewing of both the currently being recorded video and the previously recorded video from the same file with full transport control. Since the vlc.exe plays back directly from the disk file already being recorded, there is no need to set aside a large buffer just for holding the "time-shift" video data, as all other "time-shifting" mechanism require.

           

           

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