Full Transport Stream from Full-Featured DVB Cards

Disclaimer (please read!)

The author of this Howto will not be responsible for any problems or damage caused by the instructions below! If you decide to modify your DVB card, you should know what you are doing, and you are doing it on your own risk!

Introduction

On full-featured DVB cards all data transfers go through a 8 KByte dual-ported RAM (DPRAM).
The DPRAM is a bottleneck, and limits the performance of the card.

Improvements

A few years ago Roberto Deza had a great idea and developed the so called budget-patch:

• Tuner output is fed into port B of the saa7146.
• Control signal VS_B is created by the RPS of the saa7146.
• A second demux is registered to provide the full transport stream.

Unfortunately, this approach has some disadvantages:

• VS_B creation with RPS seems to be somewhat unreliable.
• CI/CAM of the card cannot be used to descramble the data stream over port B.
• The additional demux requires special actions in the application software.

The solution below avoids these problems. It is called the

Full-TS Mod

Warning: Try this only if you are experienced enough and have the equipment for SMD soldering!

Use the following pictures to locate the required signals on the pcb (marked with red arrows).

Signals to av7110 (from tuner/CI):

Note: For convenience all signals have been assigned the name of the corresponding saa7146 pin.

Port B of the saa7146:

VS_B signal generation

Obviously there are all signals available except for VS_B.
VS_B can be created using the following circuit:

For the prototype the chips were simply glued to the pcb upside-down and wired accordingly,
but you might also create a small pcb for this circuit.

Putting the pieces together

Now connect the signals:

signal name	from	to
D1_B0	av7110	saa7146 pin 145
D1_B1	av7110	saa7146 pin 146
D1_B2	av7110	saa7146 pin 147
D1_B3	av7110	saa7146 pin 148
D1_B4	av7110	saa7146 pin 151
D1_B5	av7110	saa7146 pin 152
D1_B6	av7110	saa7146 pin 153
D1_B7	av7110	saa7146 pin 154
LLC_B	av7110	saa7146 pin 157
VS_B	74HC74 pin 5	saa7146 pin 158
HS_B	av7110	saa7146 pin 159, 74HC4040 pin 10, 74HC74 pin 3
PXQ_B	av7110	saa7146 pin 160

(See schematic for connections between 74HC4040 and 74HC74. Do not forget GND and 3V3!)

Please double check that all wires are connected properly and you did not produce any shortcuts.

The picture below shows the prototype (rev 1.3):

A better looking one (rev 1.5):

Software

First test the card with the standard driver. The card should work as before.
If not: Turn off the machine and find out what's wrong!

Then install the latest v4l-dvb HG driver (or Linux Kernel >= 2.6.28) and load the driver with option 'full_ts=1'.
Everything should work as before, except that the bandwidth limitations are gone!

If you would like to avoid the parameter 'full_ts=1', you may use the script patch_eeprom_fullts to write the 'full-ts signature' to the eeprom.
Please make sure that you specify the i2c bus of the modded card! Do not use this tool unless you know what you are doing!
(The tool unpatch_eeprom may be used to remove the signature.)

Have a lot of fun!

Supported Hardware

• DVB-S rev 1.3
• DVB-S rev 1.5
• DVB-S rev 1.6
• DVB-S rev 2.1
• DVB-S rev 2.2
• DVB-S rev 2.3
• DVB-S rev B

• DVB-C rev 2.1

Note that the modification might work for other board revisions, too. Please report success or failure.

For DVB-S rev 2.2/2.3 cards port B of the saa7146 is already connected to the av7110.
Basically you just have to solder two chips onto the board:

• DVB-S rev 2.2: 1x 74HC74 (TSSOP), 1x 74HC4040 (SO-16), 2x 100nF capacitor.
• DVB-S rev 2.3: 1x 74HC74 (TSSOP), 1x 74HC4040 (TSSOP).

Credits

Special thanks go to Roberto Deza for inventing the budget-patch.