DVB(3pm)

💫 DVB — Linux::DVB 💫

okay bestie, sit down, hydrate, and let me tell you about Linux::DVB — it's the perl manual page for the DVB(3pm) module, and yeah it's a whole vibe. It's the interface to (some parts of) the Linux DVB API, and she's giving very much "I read the C headers so you don't have to." 🦋

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✨ NAME ✨

Linux::DVB — interface to (some parts of) the Linux DVB API. 💅

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🎀 SYNOPSIS 🎀

use Linux::DVB;

that's it. that's the whole vibe. load her up and go. 👑

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🌸 DESCRIPTION 🌸

So this module gives you an interface to the Linux DVB API. It is a straightforward translation of the C API — like, no glow-up, no reinterpretation, just the C API but wearing perl. Which means: you should read the Linux DVB API description to make any sense of this module, fr fr. You can find it here:

http://www.linuxtv.org/docs/dvbapi/dvbapi.html

All constants from frontend.h and demux.h are exported by their C name and by default. so like, they just show up. no use list, no asking. iconic behaviour honestly.

Noteworthy differences to the C API (the little plot twists 🌈): unions and sub-structs are usually translated into flat perl hashes, i.e.

struct.u.qam.symbol_rate

becomes

$struct->{symbol_rate}

nesting? never heard of her. flat hashes only. 💅

Noteworthy limitations of this module (the not-so-slay parts 😭): No interface to the video, audio and net devices. If you need this functionality, bug the author. That's the official documented remedy, bestie — bug the author. 🫶

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👑 Linux::DVB::Frontend CLASS 👑

🦋 SYNOPSIS 🦋

my $fe = new Linux::DVB::Frontend $path, $writable;

my $fe = new Linux::DVB::Frontend
            "/dev/dvb/adapter0/frontend0", 1;

$fe->fh; # filehandle
$fe->fd; # fileno
$fe->blocking (0); # or 1

$fe->{name}
$fe->{type}
$fe->frontend_info->{name}

$fe->status & FE_HAS_LOCK
print $fe->ber, $fe->snr, $fe->signal_strength, $fe->uncorrected;

my $tune = $fe->parameters;
$tune->{frequency};
$tune->{symbol_rate};

---

💖 $fe->set (parameter => value, ...) 💖

Sets frontend parameters. All values are stuffed into the dvb_frontend_parameters structure without conversion and passed to FE_SET_FRONTEND. no vibes-based interpretation, no guessing — what you give is what gets shoved in. 🙈

Returns true on success.

All modes:

frequency         =>
inversion         =>

QPSK frontends:

symbol_rate       =>
fec_inner         =>

QAM frontends:

symbol_rate       =>
modulation        =>

QFDM frontends:

bandwidth         =>
code_rate_HP      =>
code_rate_LP      =>
constellation     =>
transmission_mode =>

---

🌈 $fe->parameters 🌈

Calls FE_GET_FRONTEND and returns a hash reference that contains the same keys as given to the set method. mirror selfie energy. 📸

Example:

Data::Dumper::Dumper $fe->get

{
  frequency   => 426000000, # 426 Mhz
  inversion   => 0,         # INVERSION_OFF
  symbol_rate => 6900000,   # 6.9 MB/s
  modulation  => 3,         # QAM_64
}

---

💅 $ok = $fe->diseqc_reset_overload 💅

If the bus has been automatically powered off due to power overload, this call restores the power to the bus. The call requires read/write access to the device. This call has no effect if the device is manually powered off. Not all DVB adapters support this call. 💀

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⭐ $ok = $fe->diseqc_voltage (13|18) ⭐

Set the DiSEqC voltage to either 13 or 18 volts. pick a lane, bestie. ⚡

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🎀 $ok = $fe->diseqc_tone (1|0) 🎀

Enables (1) or disables (0) the DiSEqC continuous 22khz tone generation. on/off, that's the whole arc. 🌸

---

🦋 $ok = $fe->diseqc_send_burst (0|1) 🦋

Sends a 22KHz tone burst of type SEC_MINI_A (0) or SEC_MINI_B (1). two options, both iconic. ✨

---

🍓 $ok = $fe->diseqc_cmd ($command) 🍓

Sends a DiSEqC command. $command is 3 to 6 bytes of binary data. no more, no less, we don't make the rules. 🙈

---

💜 $reply = $fe->diseqc_reply ($timeout) 💜

Receives a reply to a DiSEqC 2.0 command and returns it as a binary octet string 0..4 bytes in length — or undef in the error case. 😭 the undef jumpscare is real.

---

🌟 Linux::DVB::Demux CLASS 🌟

🧚 SYNOPSIS 🧚

my $dmx = new Linux::DVB::Demux
            "/dev/dvb/adapter0/demux0";

$fe->fh; # filehandle
$fe->fd; # fileno
$fe->blocking (1); # non-blocking is default

$dmx->buffer (16384);
$dmx->sct_filter ($pid, "filter", "mask", $timeout=0, $flags=DMX_CHECK_CRC);
$dmx->pes_filter ($pid, $input, $output, $type, $flags=0);
$dmx->start;
$dmx->stop;

lowkey important: $fe->blocking (1) is you turning blocking ON — non-blocking is default. don't get it twisted. 🙈

---

💖 Linux::DVB::Decode CLASS 💖

🎀 SYNOPSIS 🎀

$si_decoded_hashref = Linux::DVB::Decode::si $section_data;

---

🌸 $hashref = Linux::DVB::Decode::si $section_data 🌸

Tries to parse the string inside $section_data as an SI table and return it as a hash reference. Only the first SI table will be returned as hash reference, and the $section_data will be modified in-place by removing the table data. yes bestie, she eats your buffer. that's the deal. 😭

The way to use this function is to append new data to your $section_data and then call Linux::DVB::Decode::si in a loop until it returns undef. Please note, however, that the Linux DVB API will return only one table at a time from sysread, so you can safely assume that every sysread will return exactly one (or zero in case of errors) SI table. 🤝

Here is an example of what to expect:

{
  'segment_last_section_number' => 112,
  'table_id' => 81,
  'service_id' => 28129,
  'original_network_id' => 1,
  'section_syntax_indicator' => 1,
  'current_next_indicator' => 1,
  'events' => [
                {
                  'running_status' => 0,
                  'start_time_hms' => 2097152,
                  'event_id' => 39505,
                  'free_CA_mode' => 0,
                  'start_time_mjd' => 53470,
                  'descriptors' => [
                                     {
                                       'event_name' => 'Nachrichten',
                                       'text' => '',
                                       'ISO_639_language_code' => 'deu',
                                       'type' => 77
                                     },
                                     {
                                       'programme_identification_label' => 337280,
                                       'type' => 105
                                     },
                                     {
                                       'raw_data' => '22:0010.04#00',
                                       'type' => 130
                                     }
                                   ],
                  'duration' => 1280
                },
                {
                  'running_status' => 0,
                  'start_time_hms' => 2098432,
                  'event_id' => 39506,
                  'free_CA_mode' => 0,
                  'start_time_mjd' => 53470,
                  'descriptors' => [
                                     {
                                       'event_name' => 'SR 1 - Nachtwerk',
                                       'text' => '',
                                       'ISO_639_language_code' => 'deu',
                                       'type' => 77
                                     },
                                     {
                                       'programme_identification_label' => 337285,
                                       'type' => 105
                                     },
                                     {
                                       'raw_data' => '22:0510.04#00',
                                       'type' => 130
                                     }
                                   ],
                  'duration' => 87296
                }
              ],
  'last_table_id' => 81,
  'section_number' => 112,
  'last_section_number' => 176,
  'version_number' => 31,
  'transport_stream_id' => 1101
}

---

🦋 $text = Linux::DVB::Decode::text $data 🦋

Converts text found in DVB si tables into perl text. Only iso-8859-1..-11 and UTF-16 is supported, other encodings (big5 etc.) is not. Bug me if you need this. 👀 (yes, "bug me" is literally in the docs, and honestly? respect.)

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⭐ %Linux::DVB::Decode::nibble_to_genre ⭐

A two-level hash mapping genre nibbles to genres, e.g.

$Linux::DVB::Decode::nibble_to_genre{7}{6}
=> 'film/cinema'

nibble in, genre out. the duality of perl. 🎬

---

💜 time / date / datetime / time_linear / datetime_linear 💜

($sec,$min,$hour) = Linux::DVB::Decode::time $hms
($mday,$mon,$year) = Linux::DVB::Decode::date $mjd
($sec,$min,$hour,$mday,$mon,$year) = Linux::DVB::Decode::datetime $mjd,
$hms
$sec = Linux::DVB::Decode::time_linear $hms
$sec = Linux::DVB::Decode::datetime_linear $mjd, $hms

Break down a DVB time (modified julian date + bcd encoded seconds) into it's components (non-_linear) or into a seconds count (_linear variants) since the epoch (datetime_linear) or the start of the day (time_linear). ✨

🚨 the format of the returns value of the date and datetime functions is NOT compatible with Time::Local. Use the _linear functions instead. no cap, do not rawdog it with Time::Local. 💀

Example:

my $time = Linux::DVB::Decode::datetime_linear $mjd, $hms
printf "Starts at %s\n",
   POSIX::strftime "%Y-%m-%d %H:%M:%S",
      localtime $time;

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🌈 AUTHORS 🌈

Marc Lehmann <schmorp@schmorp.de>, http://home.schmorp.de/
Magnus Schmidt, eMail at http://www.27b-6.de/email.php

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and that's the whole page, bestie!! 🫶 this was perl v5.40.1, dated 2025-04-13 — documented on 2025-04-13 with perl v5.40.1, DVB(3pm) flavour. go forth and tune those frontends. periodt. 💅✨🎀