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.

 

  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 logic.

 

  1. What Are Benefits of Hardware MPEG Decoding?

(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.

 

  1. Compared with MPEG2, what Advantages and Disadvantages MPEG4 inc. H.264/AVC etc. Has?

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.

 

  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 MPEG2/4 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

          See Sample MPEG1 Video Clip

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