=Paper=
{{Paper
|id=Vol-1538/paper-06
|storemode=property
|title=Transport Stream Generator and Player for Digital Terrestrial Television ISDB-Tb
|pdfUrl=https://ceur-ws.org/Vol-1538/paper-06.pdf
|volume=Vol-1538
|authors=Gonzalo Olmedo,Freddy Acosta,Nancy Paredes,Roberto Mena
|dblpUrl=https://dblp.org/rec/conf/latincom/OlmedoAPM15
}}
==Transport Stream Generator and Player for Digital Terrestrial Television ISDB-Tb==
https://ceur-ws.org/Vol-1538/paper-06.pdf
7th Latin American Workshop On Communications - 2015
Transport Stream Generator and Player for Digital Terrestrial Television
ISDB-Tb
Gonzalo Olmedo, Roberto Mena, Freddy Acosta and Nancy Paredes
Department of Electrical and Electronic
Universidad de las Fuerzas Armadas ESPE
gfolmedo@espe.edu.ec, menaroberto@hotmail.com, fracosta@espe.edu.ec, niparedes@espe.edu.ec
Servicio
Portatil
–
One
S egment
Abstract— The current paper introduces software, named Celina,
Servicio
Fijo/Movil
that integrates the three ISDB-Tb standard functional blocks: Codificacion
Source coding block, multiplex block and transmission coding Codificación
de
Video
Codificación
de
Audio
Codificación
de
Video
de
Fuente
Codificación
de
Datos
block. Celina allows to generate the MPEG-2 Transport Stream and MPEG-‐4 HE
-‐
AAC H.264
transmit it by controlling the modulator DekTec DTU-215
functionalities. Therefore, users can manipulate transmission
parameters and can broadcast the Transport Stream previously Interfaz
Común
(Interfaz
de
flujo
de
transporte)
generated through a Radio Frequency channel.
Multiplexación
(Basada
en
Sistemas
MPEG
2) Multiplexación
The first stage of the project uses bit level operations which perform
the audio and video coding. The EWBS descriptor and the ISDB-Tb Interfaz
Común
(Interfaz
de
flujo
de
transporte
en
t ramas)
program-specific information tables are generated and implemented
Codificación
during the multiplex block. The second stage of the project handles OFDM
Segmentado
QAM/DQPSK
c on
Time
Interleave
de
Transmisión
a dynamic-link library, developed on C++, which utilize the most
important DTU-215 modulator features. All of this features are
embed in an easy- to-manage, scalable, Java graphic interface Fig. 1 ISDB-Tb Standard Estructure
application.
The ISDB-Tb source coding block stablishes that fixed
Key Words— ENCODER, ISDB-TB, MODULATOR, MUX, reception services use MPEG-4 and one-segment services uses
TRANSPORT STREAM, GRAPHIC USER INTERFACE. H.264 as the compression method. Audio compression, both
fixed and mobile, is defined by the HE-ACC method.
I. INTRODUCTION
In the multiplex block, like the Japanese standard, the video,
DTT (Digital Terrestrial Television) is the combination of audio and data content are multiplexed in a single TS
technological solutions that afford transmission and reception (Transport Stream). Transport Stream is a standard container
of motion pictures, sound and data in a stream of digital format for transmission and storage of audio, video, and
signals through a network of terrestrial repeaters. On March Program and System Information Protocol (PSIP) associated to
26th, 2010 Ecuador adopted the Brazilian-Japanese standard the MPEG-2 ISO/IEC 13818-1 standard [1]. There are several
ISDB-Tb (International System Digital Broadcasting, professional tools in the market that generate Transport
Streams and manipulate packets. For example, Open Caster,
Terrestrial, Brazilian version) as the official standard for
which is an open-source software [2], has been used to test
digital terrestrial television. Currently, cities like Quito and
DTT signals and research projects thanks to the ISDB-Tb
Guayaquil are broadcasting testing signals using this digital
adaptation developed by LIFIA1 at the Universidad Nacional
technology. de la Plata [3].
Because of features like the One-Segment service embedded
The transmission coding block stablishes the coding,
into the same bandwidth, high reliability of the fixed/mobile
modulation and techniques to decrease impulsive noise,
reception, robustness against the multi-path effect and EWBS attenuation and interference effects. This block afford to
(Emergency Warning Broadcast System) used for disasters broadcast within a robust signal the generated TS. By using a
prevention makes ISDB-Tb a system with better performance digital signal, broadcast errors can be corrected and a best
than similar standards. ISDB-Tb technical structure is picture quality like HD (High Definition) can be used [4].
composed by three functional blocks which are: (1) Source
coding block, (2) Multiplex block, and (3) Transmission 1
Research lab that offers technological transference and IT services to
coding block. This subsystems are shown at figure 1. national a international communities
Copyright © 2015 for the individual papers by the papers’ authors. Copying permitted for private and academic purposes. This volume is published and
copyrighted by its editors. Latin American Workshop On Communications' 2015 Arequipa, Peru Published on CEUR-WS: http://ceur-ws.org/Vol-1538/
As other commercial solutions, Celina is a new multiplexer signals and 320x180 or 320x240 with 300kbps for LD
designed to generate and control digital television signals (Low Definition) signals.
using DekTec2 devices. Celina was developed by the ESPETV -acodec mp2 -ac 2 -ab 128000 -ar 48000 stablishes
research group at the Universidad de la Fuerzas Armadas - MPEG2 as audio encoder, with stereo channel (1 mono,
ESPE. Celina is a multiplatform tool, which its current version 2 estéreo) and a transfer rate of 128 kbps and 48kHz.
was developed to work over Windows Operating System. -muxrate 29.958294M -f mpegts out.ts determines that
a TS named out.ts is generated. This TS has a transfer
rate of 29,95Mps with null packets as the ISDB-T
II. VIDEO AND AUDIO COMPRESSION standard requires [4].
The generated file out.ts has TS packets of 188 bytes each.
Audio and video compression is achieved using FFMPEG3.
This packets contain the audio and video PES (Packetized
FFMPEG is open-source software that permits to record,
Elementary Stream) that are used to generate the data stream
encode and stream audio and video files. Furthermore, it can
according to the ISDB-Tb system [4].
work over several operating systems using a command line
interface. In the current project, the Java application uses a
Runtime class and generates a .bat file for Windows in order
to execute the commands that FFPMEG requires. III. PSI/SI TABLES AND SERVICES GENERATION
In the GUI (Graphic User Interface) developed, the Input The PSI/SI (Program Specific Information / Service
tab allows to select the .mp4, .avi or .mov file that will be Information) data permits the receiver to identify and correctly
encoded. Subsequently, the video and audio encoder, as well decode the different services that make up the TS. The
as video resolution, aspect ratio and audio channel is selected. temporary file out.ts has the PAT (Program Association Table)
The Input tab is shown at the figure 2. table that associates the included programs into the TS. Also
contains the PMT (Program Map Table) table that links the
video and audio elements. Additionally, the out.ts file include
the PCR (Program Clock Reference) table that controls the
video and audio synchronization. All this tables are related
with their own PID (Packet Identifier), which is represented
with a 13-bits number. The out.ts file can be played by
specific programs like VLC. However, it does not contain the
required ISDB-Tb format.
In addition, Celina includes a TS analyzer that obtains the
PIDs of audio, video and PMT from the PAT data, and it
shows them in the GUI as decimal numbers like figure 3
displays.
Fig. 2 Audio and video encoding interface
According to the selected configuration, a .bat file is
generated within the FFMPEG instructions that will create the
temporary file out.ts. A instruction generated is shown below.
#!/bin/sh
ffmpeg -i '/Users/ESPETV/Desktop/prueba.mp4' -vcodec mpeg2video -s
720x576 -r 30 -b 5000k -aspect 16:9 -acodec mp2 -ac 2 -ab 128000 -ar 48000
-muxrate 29.958294M -f mpegts out.ts
where:
-vcodec mpeg2video -s 720x576 -r 25 -b 5000k -aspect Fig. 3 PMT, audio and video PIDs from the out.ts file.
16:9 identifies that MEPG2 is used as the video
encoder with a 720x576 resolution, 30 frames per
second, 5 Mbps transfer rate and 16x9 ratio aspect.
CELINA was configured to support 1920x1080 or The new PID values can be used to restructure the PAT,
1280x720 reslution with a transfer rate of 10 Mbps for PMT, PCR and every audio and video TS packet according to
HD signals, 720x480 or 640x480 resolution with a the ABNT NBR 15603-1 specification [4].
transfer rate of 5 Mbps for SD (Standard Definition)
The provider name is a variable that can be entered by the
2
Company that designs and manufacture PC cards, USB/IP devices and user through the Broadcaster tab, using the Broadcaster Name
software for the digital television professional market.
3
http://www.ffmepg.org
option as figure 4 shows. In addition, in the same figure it can
be observed that the user has the option to include the Network variables that are compatible with the ISDB-Tb standard and
Name, TS Name and Virtual Channel. The Virtual Channel the DTU-215 modulator.
option is important because broadcasters can transmit on any
other frequency and maintain the same channel number as The development of the DTU-215 modulator control
their current analog channel. platform consists of two parts: a DLL (Dynamic Link Library)
developed on C++ that uses the DTAPI functions, and a Java
application that includes the C++ DLL, the TS generation part
and an easy-to-use GUI. The figure 6 shows the different
layers of abstraction used on the current project. The two
higher layers were developed in Celina.
Java
application
a nd
GUI
C++
Dynamic
L ink
Library
Fig. 4 BROADCASTER Menu.
DTAPI
The EWBS tab can active the EWBS emergency system by
configuring the12-bits area code that modifies the PMT data
and includes the emergency descriptor [5]. As figure 5 shows, DTU
215
W DM
D evice
Driver
Celina suggests the 0x0A3D or 2621 code by default. This
code is the global area for Brazil and it is used because it was
configured in the receivers used for lab testing. The emergency
signal was configured to be activated after the first quarter of
the video has passed.
The MPEG2-TS Multiplexer button generates a ready to
Fig. 6 Abstraction layers of CELINA
transmit TS for both standards ISDB-T and ISDB-Tb. The
temporary file out.ts stays in memory for new configurations
The Java application has 3 classes that permit to interact with
until a new file is loaded or the program is closed.
the user, validate data and communicate with the DLL
developed. Below there is a description of each class
developed.
IntegraJNI: It contains the variables and methods that
are used in the DLL. This class only declares the native
methods in Java; the implementation is done in the C++
DLL.
ReproduccionVideo: It is a Runnable class that takes
the previously configured and validated data, and used
it to configure the transmission parameters and transmit
the TS.
TSGen: It is the main class that contains all the GUI
Fig. 5 EWBS Menu. objects and local methods. It uses the objects of the
previously mentioned classes. In this class the
generation of the TS is made.
IV. DEKTEC MODULATOR
Java and C++ integration was made using the JNI tool. JNI
The DTU-215 DekTec modulator and the DTAPI (DekTec specifies the communication protocol between a Java code and
Application Programing Interface) are used for the an external native code written in other language. Celina uses
transmission coding block. DTAPI enables application JNI to connect the DLL with the Java application. This allow
programs to access the functions of DekTec Devices at a users to control the DekTec device using the GUI of the Java
higher level of abstraction than would be possible using direct application.
device-driver calls [8]. The DTAPI is a collection of C++
classes, each representing a generic hardware function that The software development that controls the modulator was
afford the use of several digital television standards as well as design to make the most of the DCTU-215 features. The DLL
other DekTec devices. Celina only uses those classes and has 14 methods which made the logical connection,
configuration, transmission and other functionalities that
permit to broadcast Transport Streams and Broadcast
Transport Streams. Below it is listed several of the previously
mentioned methods.
String LeerError(): If there is any, it allows to read
errors produced when a process has occur between the
DTAPI and the modulator. C++ returns a String variable
within the error message event.
Fig. 7 Test scenario for transmission and reception of the ISDB-Tb
boolean AdjuntarTarjeta(): It permits to initialize the
signal
connection between the PC that host Celina and the
modulator.
boolean ConectarPuerto(): It permits to begin upper The TS generated, named prueba.ts, is transmitted by the
layer communication with the transmission port. Dektec DTU-215 modulator, through the physical channel
boolean LimpiarBanderas(): It resets the internal error- number 30 on the 569,143 MHz frequency. The modulation
control flags of the DTU-215 modulator. parameters are configured, as well as the guard time,
boolean Configuracion_Tx_TodoCapaA(boolean interleaving time, encoding and mode. Figure 8 shows the
flag_TMCC, int[] valores_confg): It perform the configuration of the previously mentioned parameters.
transmission parameters configuration. It sends from
Java to C++ an array of int variables that contain the
required information of how the TS will be transmitted.
The data that was sent, has a meaning according to its
position in the array.
boolean AbrirArchivo(String ts_path): It takes a String
variable with the path and name of the TS and uses to
open the file
boolean InitTxParams(double frecuency, int size_pack,
int nivelDbm): This method perform the configuration
of the frequency where the TS will be transmitted, also it
defines if the TS packets have 188 or 204 bytes in order
to get them ready for the transmission.
boolean ReproducirTs(int wrap): This method performs Fig. 8 Configuration of the transmission parameters
the transmission of the TS with the previously
mentioned configuration. The only Java parameter send Once the signal is transmitted, Figure 9 shows the Transport
is an indicator that afford the wrap option. Stream reception, the same that presented full synchronization
boolean PararTs(): It permits to stop the TS transmission without freezes, and the channel name “TIC EC”, in channel
boolean CerrarPrograma(): It performs the logical 30.1 can be seen, as it was configured.
disconnection, reset the flags, erase any data in the
buffer to end the communication with the DTU-215
modulator.
int ValidarArchivoTS(): It permits to validate the
selected file as a TS by checking its packet size.
V. RESULTS
To carry out the tests, the scenario consist of a Dell PC Core
I5 1.7GHz with 4GB of RAM, which is connected to the USB
cable of the Dektec DTU-215 modulator. The output port of
the modulator is connected to a signal amplification device and
Fig. 9 Digital TV image reception
then to a splitter which connects to the Agillent CXA Digital
TV Analyzer and to a TV that contains the included ISDB-Tb The Agillent analyzer verifies that the transmission signal is
decoder. indeed the center frequency mentioned above, and the
bandwidth of the channel is 6MHz as indicated by the ISDB-
Tb standard.
REFERENCES
[1] ABNT NBR 15603-2, "Televisão Digital Terrestre -
Multiplexação e serviços de informação (SI) Sintaxes e
definições da informação básica de SI", first edition,
December 2007
[2] OpenCaster the free digital tv software, “Descarga del
manual de OpenCaster”. November 2011. [Online]
Fig. 10 Bandwidth transmission and Frequency verification http://www.avalpa.com/the-key-values/15-free-software/
33-opencaster.
[3] OpenCaster para SADTV Lifia, “Manual de OpenCaster
To test the emergency signal, a Japanese decoder, brand para SADTV”. November 2011. [Online].
PIXELA4, was connected. The bit of the emergency signal in http://wiki.ginga.org.ar/lib/exe/fetch.php?media=lifia:guia
the TMCC (Transmission and Multiplexing Configuration opencaster.pdf.
Control) of the modulator was activated, as shown in the [4] Televisión Digital Argentina, “Ventajas Televisión
Figure 11, there is the emergency signal activation. Digital”. January 2011 [Online]
http://www.minplan.gov.ar/html/tv_digital/a.php, 2010,
[5] ARIB STANDARD, Service Information for Digital Broadcaster
System, ARIB SDT-B10, 2008.
[6] L. Soares, S. Barbosa, Programando en NCL 3.0, PUC-RIO,
2012
[7] ANATEL, ABNT NBR 15601, Sistema de transmisión de
la norma Brasileña para Televisión Digital Terrestre,
2007.
[8] DekTec Digital Video. (2011). DTAPI – C++ API for
DekTec Devices.
[9] Dektec Digital Video. (2014). Catálogo 2014. December
2014. [Online]
http://www.dektec.com/Products/Catalogue.pdf
Fig. 11 Reception of the emergency signal
Celina is a tool that allows the generation of a TS, including
the encoding and multiplexing stage. It builds the PAT, PMT,
PRC, SDT and NIT tables based on the Broadcasters’
requirements. It includes the generation of the EWBS
emergency signal, which activates audible alarms in decoders,
as well as it turns on the decoders, based on established code
in the program which must match the receiver.
Celina allows the transmission of the previously generated
TS, considering that settings as: transmission frequency,
channel bandwidth, service distribution in hierarchical layers,
hierarchical layers modulation, etc. all comply the ISDBT-Tb
standard applicable regulations.
Celina was designed as a training support tool. It works at
the bit level, allowing a large number of configurations
according to future requirements. For example, it increases the
number of emergency codes or modifies tables’ parameters
presented with fixed values. In future versions, Celina will
support the possibility of multiple programming, Ginga
Applications data and the generation BTS integrated with
ISDB-T and ISDB-Tb DekTec modulators.
4
Peripheral PC hardware and multimedia software manufacturer