Digital Signal Processing Reference
In-Depth Information
An Implementation of Real-Time Audio Monitoring
in Network Camera
Xuehao Yuan
1,2
, Yumeng Zhang
1,2
, and Hui Li
1,2,*
1
Shenzhen Key Lab of Cloud Computing & Application, Shenzhen Graduated School,
Peking University, Shenzhen, China 518055
2
Engineering Lab of Converged Network Technology, Shenzhen Graduated School,
Peking University, Shenzhen, China 518055
yuanxuehao@sz.pku.edu.cn, zhangyumeng06@gmail.com,
lih64@pkusz.edu.cn
Abstract.
Basis on the network camera, audio encoding and RTMP protocol, an
audio module in network camera based on Ambarella A5s platform is designed
and implemented to meet the increasing need of real-time audio in safety moni-
toring and live broadcast field. After audio captured by ALSA API and encoded
by AAC API, audio data and video data are added timestamps to respectively
for synchronization and then transmitted to web server in the form of RTMP
packet. This solution can efficiently make up for the deficiency of traditional
camera in audio capture, encoding and network transmission.
Keywords:
network camera, audio, A5s, ALSA, AAC, RTMP.
1
Introduction
Network camera [1] is a product of new generation combining traditional camera and
network video technology and a low-cost solution for remote audio and video trans-
mission. It has obvious advantages over traditional analog camera such as high defini-
tion, high integration and low total cost of ownership. Additionally, networking, digi-
tization and intelligence also make network camera a better choice.
Audio information is becoming of increasing importance to some applications of
network camera rapidly such as audio evidence in security monitoring system and live
broadcast. For analog camera, audio-supported function must be implemented only by
means of extra audio wiring. However, network camera can capture audio signal
through front-end audio device, synchronize digitized and compressed audio data with
video data, and finally transfer audio and video data to RTMP server through net-
work. Real-time audio and video situation can be monitored by browser or client
software very conveniently, as displayed in Fig.1.
*
Corresponding author.
