[FFmpeg-devel] [PATCH] avformat/mpegtsenc: Add option to mark stream begin as discontinuous

[Steven Liu]

2016-11-02 7:51 GMT+08:00 Michael Niedermayer <michael at niedermayer.cc>:

> This avoids continuity check failures in concatenated streams
>
> TODO: docs
>
> Signed-off-by: Michael Niedermayer <michael at niedermayer.cc>
> ---
>  libavformat/mpegtsenc.c | 26 ++++++++++++++++++++++++++
>  1 file changed, 26 insertions(+)
>
> diff --git a/libavformat/mpegtsenc.c b/libavformat/mpegtsenc.c
> index 3ad3de7..71a6642 100644
> --- a/libavformat/mpegtsenc.c
> +++ b/libavformat/mpegtsenc.c
> @@ -46,6 +46,7 @@
>  typedef struct MpegTSSection {
>      int pid;
>      int cc;
> +    int discontinuity;
>      void (*write_packet)(struct MpegTSSection *s, const uint8_t *packet);
>      void *opaque;
>  } MpegTSSection;
> @@ -104,6 +105,7 @@ typedef struct MpegTSWrite {
>  #define MPEGTS_FLAG_AAC_LATM        0x02
>  #define MPEGTS_FLAG_PAT_PMT_AT_FRAMES           0x04
>  #define MPEGTS_FLAG_SYSTEM_B        0x08
> +#define MPEGTS_FLAG_DISCONT         0x10
>      int flags;
>      int copyts;
>      int tables_version;
> @@ -153,6 +155,12 @@ static void mpegts_write_section(MpegTSSection *s,
> uint8_t *buf, int len)
>          *q++  = s->pid;
>          s->cc = s->cc + 1 & 0xf;
>          *q++  = 0x10 | s->cc;
> +        if (s->discontinuity) {
> +            q[-1] |= 0x20;
> +            *q++ = 1;
> +            *q++ = 0x80;
> +            s->discontinuity = 0;
> +        }
>          if (first)
>              *q++ = 0; /* 0 offset */
>          len1 = TS_PACKET_SIZE - (q - packet);
> @@ -223,6 +231,7 @@ typedef struct MpegTSWriteStream {
>      struct MpegTSService *service;
>      int pid; /* stream associated pid */
>      int cc;
> +    int discontinuity;
>      int payload_size;
>      int first_pts_check; ///< first pts check needed
>      int prev_payload_key;
> @@ -782,6 +791,7 @@ static int mpegts_init(AVFormatContext *s)
>          service->pmt.write_packet = section_write_packet;
>          service->pmt.opaque       = s;
>          service->pmt.cc           = 15;
> +        service->pmt.discontinuity= ts->flags & MPEGTS_FLAG_DISCONT;
>      } else {
>          for (i = 0; i < s->nb_programs; i++) {
>              AVProgram *program = s->programs[i];
> @@ -800,6 +810,7 @@ static int mpegts_init(AVFormatContext *s)
>              service->pmt.write_packet = section_write_packet;
>              service->pmt.opaque       = s;
>              service->pmt.cc           = 15;
> +            service->pmt.discontinuity= ts->flags & MPEGTS_FLAG_DISCONT;
>              service->program          = program;
>          }
>      }
> @@ -808,11 +819,13 @@ static int mpegts_init(AVFormatContext *s)
>      /* Initialize at 15 so that it wraps and is equal to 0 for the
>       * first packet we write. */
>      ts->pat.cc           = 15;
> +    ts->pat.discontinuity= ts->flags & MPEGTS_FLAG_DISCONT;
>      ts->pat.write_packet = section_write_packet;
>      ts->pat.opaque       = s;
>
>      ts->sdt.pid          = SDT_PID;
>      ts->sdt.cc           = 15;
> +    ts->sdt.discontinuity= ts->flags & MPEGTS_FLAG_DISCONT;
>      ts->sdt.write_packet = section_write_packet;
>      ts->sdt.opaque       = s;
>
> @@ -883,6 +896,7 @@ static int mpegts_init(AVFormatContext *s)
>          ts_st->payload_dts     = AV_NOPTS_VALUE;
>          ts_st->first_pts_check = 1;
>          ts_st->cc              = 15;
> +        ts_st->discontinuity   = ts->flags & MPEGTS_FLAG_DISCONT;
>          /* update PCR pid by using the first video stream */
>          if (st->codecpar->codec_type == AVMEDIA_TYPE_VIDEO &&
>              service->pcr_pid == 0x1fff) {
> @@ -1078,6 +1092,10 @@ static void mpegts_insert_pcr_only(AVFormatContext
> *s, AVStream *st)
>      /* Continuity Count field does not increment (see 13818-1 section
> 2.4.3.3) */
>      *q++ = TS_PACKET_SIZE - 5; /* Adaptation Field Length */
>      *q++ = 0x10;               /* Adaptation flags: PCR present */
> +    if (ts_st->discontinuity) {
> +        q[-1] |= 0x80;
> +        ts_st->discontinuity = 0;
> +    }
>
>      /* PCR coded into 6 bytes */
>      q += write_pcr_bits(q, get_pcr(ts, s->pb));
> @@ -1195,6 +1213,11 @@ static void mpegts_write_pes(AVFormatContext *s,
> AVStream *st,
>          *q++      = ts_st->pid;
>          ts_st->cc = ts_st->cc + 1 & 0xf;
>          *q++      = 0x10 | ts_st->cc; // payload indicator + CC
> +        if (ts_st->discontinuity) {
> +            set_af_flag(buf, 0x80);
> +            q = get_ts_payload_start(buf);
> +            ts_st->discontinuity = 0;
> +        }
>          if (key && is_start && pts != AV_NOPTS_VALUE) {
>              // set Random Access for key frames
>              if (ts_st->pid == ts_st->service->pcr_pid)
> @@ -1872,6 +1895,9 @@ static const AVOption options[] = {
>      { "system_b", "Conform to System B (DVB) instead of System A (ATSC)",
>        0, AV_OPT_TYPE_CONST, { .i64 = MPEGTS_FLAG_SYSTEM_B }, 0, INT_MAX,
>        AV_OPT_FLAG_ENCODING_PARAM, "mpegts_flags" },
> +    { "initial_discontinuity", "Mark initial packets as discontinuous",
> +      0, AV_OPT_TYPE_CONST, { .i64 = MPEGTS_FLAG_DISCONT }, 0, INT_MAX,
> +      AV_OPT_FLAG_ENCODING_PARAM, "mpegts_flags" },
>      // backward compatibility
>      { "resend_headers", "Reemit PAT/PMT before writing the next packet",
>        offsetof(MpegTSWrite, reemit_pat_pmt), AV_OPT_TYPE_INT,
> --
> 2.10.2
>
>
LGTM

Thanks

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