[FFmpeg-devel] [PATCH] DVB EPG decoder

[Anthony Delannoy]

> I think we should only merge the part of this patchset which makes the EIT
> available as a data stream. Parsing the whole EIT or dumping the data as
> ASCII is not libavcodec's or libavutil's job.

The EPG decoder does not change the table's data, it just store them
and it happens to
contains text sometimes.
Some utilites functions I made in libavutil/dvb can convert those raw
data in text
description(s) for certain descriptors.

> Also there is no such concept in libavcodec as a data decoder, if something happens to
> work with avcodec_send_packet/avcodec_receive_frame that is mostly luck I
> believe.

avcodec_send_packet and avcodec_receive_frame both call
AVCodec::receive_frame if it is
implemented. That's why my implementation of the EPG decoder does
contain this function.

For now my test scripts consists to:
```
 99         if (st->codecpar->codec_id != AV_CODEC_ID_EPG)
100             goto free_pkt;
101
102         ret = avcodec_send_packet(dec_ctx, &pkt);
...
112         while (1) {
113             ret = avcodec_receive_frame(dec_ctx, frame);
114             if (ret < 0)
115                 break;
116
117             for (int i = 0; i < frame->nb_side_data; i++) {
118                 AVFrameSideData *sd = frame->side_data[i];
119                 if (sd && sd->type == AV_FRAME_DATA_EPG_TABLE) {
120                     EPGTable *table = sd->data;
121                     av_epg_show_table(table, AV_LOG_WARNING);
122                 }
123             }
124             av_frame_unref(frame);
125         }
126
127 free_pkt:
128         av_packet_unref(&pkt);
```
It works as intended and permits to decode EPGTable without issues, I
tried on multiple channels.

I wanted to permit the table decoding and not just an EPG data stream
to permit easy reading
and in the future easy modification before encoding EPG back.

> I am also not sure if we should add the EIT PID to all programs, that
> would mess up the direct relation between a PMT and an AVProgram, and we
> probably don't want that. So I'd rather see the EIT data stream as a
> standalone PID separate from the programs.

I'm not an expert but I think each service/program contains a PMT
table and all others. So one
EPG stream (if available) for each service.
That's what I understood from the ETSI EN 300 468 V1.16.1