[FFmpeg-devel] [PATCH] DVB EPG decoder

[Anthony Delannoy]

Okay, thanks

I will patch that

Le sam. 24 août 2019 à 20:09, Marton Balint <cus at passwd.hu> a écrit :
>
>
> On Fri, 23 Aug 2019, Anthony Delannoy wrote:
>
> >> 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
>
> The EPG stream is a single stream in the whole TS, it is on a single PID.
> The PMTs do not reference the EIT PID, therefore we should not make the
> EPG stream part of the programs, even if the EPG stream can contain the
> schedule of the programs.
>
> Regards,
> Marton
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