[FFmpeg-devel] [PATCH] DVB EPG decoder

[Marton Balint]

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