This page describes a recent comparison between Darim DVMPEG 5.0 and Ligos LSX 2.5 encoders performed at Darim Vision's R&D center. A few problems were noted as described below. Click here to find out how we tested these two products. Also, the results of the test are available for free downloading from here.

These figures depict the problem of the Ligos LSX video encoder with significant and repetitive STD buffer overflows (shown with read lines).

Most of the hardware DVD/MPEG2 players can not handle video buffer overflows gracefully - this usually results in jerky (stuttering) video playback. Software players are less sensitive, but may also produce unpredictable behavior in case of excessive overflows.

These figures depict a serious problem of the Ligos LSX audio encoder with significant and repetitive STD buffer overflows (shown with read lines).

Most of the hardware DVD/MPEG2 players can not handle audio buffer overflows gracefully - this usually results in audio distortions and/or jerky (stuttering) video playback. Software players may simply crash or hang up system in such case.

These figures show timing analysis diagram for elementary video stream (ID=224) embedded inside MPEG2 program stream. The video timing information is generated by MPEG stream multiplexer. Smooth timing is very important for proper video/audio synchronization (lip sync).

The figures show that multiplexers of both DVMPEG and Ligos LSX encoders output correct timing information. However, it is quite noticeable that DVMPEG's multiplexer produces more consistent timing with lesser deviation from expected values.

(the numbers shown are in 27 MHz clock periods)

These figures show timing analysis diagram for elementary audio stream (ID=192) embedded inside MPEG2 program stream. Audio timing information is also generated by MPEG stream multiplexer. Naturally, smooth audio timing is as important for proper lip sync as the one for video.

The figures show discrepancies between the actually encoded value and the value expected by the analyzer program based on the bitrate parameter specified in the audio stream header. Whenever the deviation exceeds a predefined tolerance value, the analyzer software records an error message into analysis log. The figure on the right shows that Ligos LSX multiplexer have produced two errors that may be a sufficient reason of audio blip or jerk in the video playback. (the numbers shown are in 27 MHz clock periods)

Lastly, the figures here show the analysis log file produced by M-Probe MPEG analyzing software. The Red circles indicate errors, that is a violation of certain aspects of ISO/IEC 13818 specification. The Blue circles are informational messages that do not indicate a problem.

As you can see the MPEG2 file produced by the Ligos LSX encoder has many problems in it, while DVMPEG 5.0 produces fully ISO standard-compliant MPEG files.

As you see the from the chart, Darim's DVMPEG 5.0 encoder is noticeably faster than its competitor under the same conditions. Also, and more importantly, the Ligos LSX software has to has to perform three sequential operations to produce the final MPEG2 program stream output. It has to encode video and audio separately and then multiplex them (mux) to add timing synchronization information. DVMPEG does that all simultaneously, thus saving time and a lot of disk space that would be needed for intermediate files.

The tests were performed on a Pentium II 400 MHz machine with 64MB RAM running Windows 95. We used a sample GOLF.AVI from DVMPEG 5.0 installation CD-ROM as a source for the described MPEG2 program stream compression. For improved performance, the AVI file was copied to a fast IDE hard disk working in UltraDMA mode 2.

We used the AVI2MPEG program provided with DVMPEG 5.0 and the following settings:

Video bitrate: 6000 Kbits/sec
Audio bitrate: 224 Kbits/sec, stereo

Advanced parameters:
quality_factor = 0, filter_mask = none,
color_temp = Low, field_frame = Deinterlaced
all other parameters were left as default

The following settings were used for Ligos LSX 2.5 encoder:

Main Profile plus:
Video bitrate: 6000 Kbits/s
Audio bitrate: 224 Kbits/s

Options:
Deinterlace input picture, Normal conversion,
Do not show output picture,
Do not calculate quality during conversion.

We have used XingDVD by Xing Technologies, Inc. software DVD/MPEG2 player and Real Magic Hollywood hardware DVD player by Sigma Designs, Inc. to perform the play back test of the resulting MPEG clip. The clip produced by Ligos LSX 2.5 encoder played jerky on the Hollywood hardware player. The XingDVD player could not play the file at all because Microsoft's MPEG2 splitter provided with DirectX Media 6.0 (a.k.a DirectShow) was unable to parse the file correctly.

Finally, the entire analysis and all figures shown here were produced by MProbe MPEG analyzer software by Interra, Inc.