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7800 MultiFrame Manual
7880DEC-H264HD H-264 HD Decoder
4.2.1. P1 Necessary for Decoding
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TS Sync Error: The most important function for the evaluation of data from the MPEG-2 TS is
the sync acquisition. The actual synchronization of the TS depends on the number of correct
sync bytes necessary for the device to synchronize; two or more consecutive corrupted sync
bytes indicate sync loss. After synchronization has been achieved the evaluation of the other
parameters is carried out.
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Sync Byte: The indicator "Sync Byte" is set as soon as the correct sync byte (0x47) does not
appear after 188 or 204 bytes. This is fundamental because this structure is used throughout
the channel encoder and decoder chains for synchronization. It is also important that every sync
byte is checked for correctness since encoders do not necessarily check the sync byte.
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PAT Error: The Program Association Table (PAT), which only appears in PID 0x0000 packets,
tells the decoder what programs are in the TS and points to the Program Map Tables (PMT)
which in turn point to the component video, audio and data streams that make up the program.
If the PAT is missing then the decoder can do nothing, no program is decodable. Nothing other
than a PAT should be contained in a PID 0x0000.
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Continuity Count: For this indicator three checks are combined. The preconditions "Incorrect
packet order" and "Lost packet" could cause problems for receivers that are not equipped with
additional buffer storage and intelligence. It is not necessary for the test equipment to
distinguish between these two preconditions as they are logically OR-ed, together with the third
precondition, "a packet occurs more than twice" into one indicator.
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PMT Error: The Program Association Table (PAT) tells the decoder how many programs there
are in the stream and points to the PMTs that contain the information where the parts for any
given event can be found. Parts in this context are the video stream (normally one), the audio
streams and the data stream (e.g. Teletext). Without a PMT the corresponding program is not
decodable.
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PID Error: It is checked whether there exists a data stream for each PID that occurs. This error
often occurs where TS are multiplexed, or demultiplexed and again remultiplexed.
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Clear P1 Error: Enabling this function will clear all of the P1 fields.
4.2.2. P2 Recommended
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Transport Error: The primary Transport error indicator is Boolean which counts the erroneous
TS packets. This counter is intended for statistical evaluation of the errors. If an error occurs, no
further error indication should be derived from the erroneous packet.
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CRC Error: The CRC check for the CAT, PAT, PMT, NIT, EIT, BAT, SDT and TOT indicates
whether the content of the corresponding table is corrupted. In this case no further error
indication should be derived from the content of the corresponding table.
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PCR Repetition: The PCRs are used to re-generate the local 27 MHz system clock. If the PCR
do not arrive with sufficient regularity then this clock may jitter or drift. The receiver/decoder may
even go out of lock. This error indicates that the time interval between two consecutive PCR
values is more than 40 ms.
7880DEC-H264HD - 24
Revision 1.0
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