User’s Manual v.15
QVidium
®
H.264 HD Video Codecs
™
Copyright 2011-2014 QVidium
®
Technologies, Inc.
Page 21 of 71
To record a single contiguous file larger than 4 Gigabytes, you must use an NTFS, Ext3, or
networked file system. Also, if you set a Maximum File Size under the Advanced Encoding tab to a
value other than Unlimited, then when a video clip exceeds this size, the encoder will automatically
close the current file and start a new file.
Video Input:
The QVPRO has two video inputs: HDMI and SDI. The QVENC has three video
inputs: SDI, Composite (CVBS), and S-Video (Y/C). The SDI input detects and automatically
switches among SD-SDI, HD-SDI, and 3G-SDI signals on the same BNC input port. However,
please note that at present, the HDMI input only works for HD video (1080i or 720p). For SD
video (480i NTSC or 576i PAL) or 1080p (50 or 60 frames per second), you must use the SDI
input. On the QVENC, the Composite and S-Video inputs only accept SD video.
Stream Bit Rate:
This sets the total output stream bit rate. The QVPRO/QVENC sets an internal
video bit rate by subtracting the audio bit rate from the Stream Bit Rate and setting an
additional margin for IP packetization. For all stream modes, the output bit rate should not
exceed this value. However, there may be a variation in output bit rate of up to about 5% over
the value you set. If the bit rate is too low for the video content you have, then you can expect
to see pixelization and blurring of the image for scenes with high motion.
Normally with the HD encoding license, the encoder will use this
Stream Bit Rate
regardless
of whether the input is SD or HD resolution. However, under the Advanced Encoding
parameters, you can set a bit rate for SD video that will automatically be used when you switch
the input to an SD feed. For HD feeds, the encoder would otherwise use the basic Stream Bit
Rate. In this way, the encoder can automatically switch between HD and SD video encoding,
with appropriate bit rates to match, by simply changing the SDI input signal.
Video Encoding:
You can select primarily between H.264 encoding (selectable profile and level,
High Profile by default) and MPEG2 (Main profile). H.264 requires about ½ to 1/3 of the bit rate
for comparable video quality versus MPEG2.
Audio Bit Rate:
This sets the total bit rate for the combination of the 2 audio channels (left and
right channels of a single audio pair). (The default of 160Kbps actually produces the same TS
Stream Bit Rate as setting the audio bit rate to 128Kbps because of size constraints for audio
packet sizes that must fit within a fixed TS packet size.)
Audio Encoding:
You can select among
MPEG1/Layer2
and
MPEG2 AAC
audio encoding
formats on the QVPRO and QVENC, and also
AC3 Pass-though on SDI
and
AC3 Pass-
through on Optical
for the QVENC. For speech and verbal content, and to maintain the
highest level of 3
rd
party compatibility, we recommend the default of MPEG1/Layer 2. For high
fidelity audio, such as music or concerts, we recommend MPEG2 AAC. In addition, the
QVENC and QVDEC support Dolby® Digital (also known as AC3) pass-through operation
selectable via either an external S/PDIF connector or embedded SDI audio. AC3 provides
Surround Sound 5.1 audio (5 channels plus one subwoofer channel), also known as Dolby
Digital.
Audio Sampling Rate:
The default is a 48KHz audio sampling rate. For SDI I/O, 48KHz is
required as part of the SMPTE 259M standard. We recommend keeping this default value
when using the SDI video input. Higher sampling rates preserve higher audio frequencies.
IP Transport:
The QVPRO/QVENC offers 3 choices: ARQ, RTP, and UDP. ARQ and RTP all
output UDP/IP packets with RTP headers. UDP transport encapsulates the MPEG Transport
Stream as the UDP/IP packet payload without the RTP data header. With the Evostream
Media Server (EMS) license, the QVENC supports RTSP, RTMP (Flash Media), and HLS
transport formats. Enabling ProMPEG FEC (SMPTE-2022) adds a ProMPEG option.
