[FFmpeg-devel] [PATCH] DVB EPG decoder

Anthony Delannoy anthony.2lannoy at gmail.com
Wed Sep 4 15:27:54 EEST 2019


Hi

I'm still interested to have those three commits merged (update in attachments).

But I'd like to see data decoder in the future to use more easily
EPG/NIT/BAT etc tables.
Will it be possible? With modifications if it needs to be?

Anthony Delannoy

Le mar. 3 sept. 2019 à 23:39, Marton Balint <cus at passwd.hu> a écrit :
>
> Hi,
>
> I am not sure if you are interested getting only patch 1, 2 and 3
> merged, but if you are, then here are my comments for patch 3.
>
> > From 025ec8e8d607d02f2e5b4021783ab8f3b42d0bc1 Mon Sep 17 00:00:00 2001
> > From: Anthony Delannoy <anthony.2lannoy at gmail.com>
> > Date: Wed, 21 Aug 2019 11:46:56 +0200
> > Subject: [PATCH 03/10] lavf/mpegts: EPG extraction from mpegts
> >
> > ---
> >  libavformat/mpegts.c | 67 ++++++++++++++++++++++++++++++++++++++++++--
> >  1 file changed, 65 insertions(+), 2 deletions(-)
> >
> > diff --git a/libavformat/mpegts.c b/libavformat/mpegts.c
> > index 47d8d5f877..03c1753ac7 100644
> > --- a/libavformat/mpegts.c
> > +++ b/libavformat/mpegts.c
> > @@ -2489,13 +2489,57 @@ static void pat_cb(MpegTSFilter *filter, const uint8_t *section, int section_len
> >      }
> >  }
> >
> > +static void eit_cb(MpegTSFilter *filter, const uint8_t *section, int section_len)
> > +{
> > +    MpegTSContext *ts = filter->u.section_filter.opaque;
> > +    MpegTSSectionFilter *tssf = &filter->u.section_filter;
> > +    const uint8_t *p, *p_end;
> > +    SectionHeader h1, *h = &h1;
> > +    int idx;
> > +    AVProgram *prg;
>
> Maybe you can check if AVStream->discard == DISCARD_ALL for the EIT stream and
> skip the packet if the stream is discarded.
>
> > +
> > +    p_end = section + section_len - 4;
> > +    p     = section;
> > +
> > +    if (parse_section_header(h, &p, p_end) < 0)
> > +        return;
> > +    if (h->tid < EIT_TID || h->tid > OEITS_END_TID)
> > +        return;
>
> > +    if (ts->skip_changes)
> > +        return;
> > +    if (skip_identical(h, tssf))
> > +        return;
>
> I don't think these last two checks (skip changes and skip identical) makes
> much sense here, just remove them.
>
> > +
> > +    idx = ff_find_stream_index(ts->stream, filter->pid);
> > +    if (idx < 0)
> > +        return;
>
> Instead of finding the stream each time, you should simply add an AVStream
> *epg_stream to MpegTsContext, set it where you create the stream, and use that
> always.
>
> > +
> > +    /**
> > +     * In case we receive an EPG packet before mpegts context is fully
> > +     * initialized.
> > +     */
> > +    if (!ts->pkt)
> > +        return;
> > +
> > +    new_data_packet(section, section_len, ts->pkt);
> > +    ts->pkt->stream_index = idx;
>
> > +    prg = av_find_program_from_stream(ts->stream, NULL, idx);
> > +    if (prg && prg->pcr_pid != -1 && prg->discard != AVDISCARD_ALL) {
> > +        MpegTSFilter *f = ts->pids[prg->pcr_pid];
> > +        if (f && f->last_pcr != -1)
> > +            ts->pkt->pts = ts->pkt->dts = f->last_pcr/300;
> > +    }
>
> This program based logic is no longer needed since EIT is not added to programs.
>
> > +    ts->stop_parse = 1;
> > +}
> > +
> >  static void sdt_cb(MpegTSFilter *filter, const uint8_t *section, int section_len)
> >  {
> >      MpegTSContext *ts = filter->u.section_filter.opaque;
> >      MpegTSSectionFilter *tssf = &filter->u.section_filter;
> >      SectionHeader h1, *h = &h1;
> >      const uint8_t *p, *p_end, *desc_list_end, *desc_end;
> > -    int onid, val, sid, desc_list_len, desc_tag, desc_len, service_type;
> > +    int onid, val, sid, desc_list_len, desc_tag, desc_len, service_type,
> > +        eit_sched, eit_pres_following;
> >      char *name, *provider_name;
> >
> >      av_log(ts->stream, AV_LOG_TRACE, "SDT:\n");
> > @@ -2525,6 +2569,24 @@ static void sdt_cb(MpegTSFilter *filter, const uint8_t *section, int section_len
> >          val = get8(&p, p_end);
> >          if (val < 0)
> >              break;
> > +        eit_sched = (val >> 1) & 0x1;
> > +        eit_pres_following = val & 0x1;
> > +
> > +        if (eit_sched | eit_pres_following) {
> > +            int idx = ff_find_stream_index(ts->stream, EIT_PID);
> > +            AVStream *st = (idx >= 0) ? ts->stream->streams[EIT_PID] : NULL;
>
> I guess ts->stream->streams[EIT_PID] wanted to be ts->stream->streams[idx] but
> it does not matter because you should rework this if you add epg_stream to
> MpegTsContext.
>
> > +
> > +            if (!st) {
> > +                st = avformat_new_stream(ts->stream, NULL);
> > +                if (!st)
> > +                    return;
> > +                st->id = EIT_PID;
> > +                st->program_num = sid;
> > +                st->codecpar->codec_type = AVMEDIA_TYPE_DATA;
> > +                st->codecpar->codec_id = AV_CODEC_ID_EPG;
> > +            }
> > +        }
> > +
> >          desc_list_len = get16(&p, p_end);
> >          if (desc_list_len < 0)
> >              break;
> > @@ -2975,8 +3037,8 @@ static int mpegts_read_header(AVFormatContext *s)
> >          seek_back(s, pb, pos);
> >
> >          mpegts_open_section_filter(ts, SDT_PID, sdt_cb, ts, 1);
> > -
> >          mpegts_open_section_filter(ts, PAT_PID, pat_cb, ts, 1);
> > +        mpegts_open_section_filter(ts, EIT_PID, eit_cb, ts, 1);
> >
> >          handle_packets(ts, probesize / ts->raw_packet_size);
> >          /* if could not find service, enable auto_guess */
> > @@ -3233,6 +3295,7 @@ MpegTSContext *avpriv_mpegts_parse_open(AVFormatContext *s)
> >      ts->auto_guess = 1;
> >      mpegts_open_section_filter(ts, SDT_PID, sdt_cb, ts, 1);
> >      mpegts_open_section_filter(ts, PAT_PID, pat_cb, ts, 1);
> > +    mpegts_open_section_filter(ts, EIT_PID, eit_cb, ts, 1);
> >
> >      return ts;
> >  }
> > --
> > 2.23.0
>
> Regards,
> Marton
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