[FFmpeg-devel] [PATCH v2] avformat/dhav: also support ZLAV packets

[Michael Keeley]

Ping :-)

> -----Original Message-----
> From: ffmpeg-devel [mailto:ffmpeg-devel-bounces at ffmpeg.org] On Behalf
> Of Michael Keeley
> Sent: Sunday, 8 November 2020 10:42 pm
> To: ffmpeg-devel at ffmpeg.org
> Cc: Michael Keeley
> Subject: [FFmpeg-devel] [PATCH v2] avformat/dhav: also support ZLAV
> packets
> 
> Some DVRs (e.g. D7008FH made by iSmart Cities (Zhuhai) Limited) output
> the same format .dav file,
> but use ZLAV/zlav tags to delimit the packets instead of DHAV/dhav.
> 
> Signed-off-by: Michael Keeley <mike at keeley.net.nz>
> ---
>  Changelog             |  1 +
>  libavformat/dhav.c    | 31 ++++++++++++++++++++++---------
>  libavformat/version.h |  2 +-
>  3 files changed, 24 insertions(+), 10 deletions(-)
> 
> diff --git a/Changelog b/Changelog
> index 0ea1901bbe..a56216543d 100644
> --- a/Changelog
> +++ b/Changelog
> @@ -41,6 +41,7 @@ version <next>:
>  - LEGO Racers ALP (.tun & .pcm) muxer
>  - AV1 VAAPI decoder
>  - adenorm filter
> +- Add ZLAV format to DHAV demuxer
> 
> 
>  version 4.3:
> diff --git a/libavformat/dhav.c b/libavformat/dhav.c
> index 53deaff77e..40c2cc78b0 100644
> --- a/libavformat/dhav.c
> +++ b/libavformat/dhav.c
> @@ -1,5 +1,5 @@
>  /*
> - * DHAV demuxer
> + * DHAV/ZLAV demuxer
>   *
>   * Copyright (c) 2018 Paul B Mahol
>   *
> @@ -57,7 +57,7 @@ static int dhav_probe(const AVProbeData *p)
>      if (!memcmp(p->buf, "DAHUA", 5))
>          return AVPROBE_SCORE_MAX;
> 
> -    if (memcmp(p->buf, "DHAV", 4))
> +    if (memcmp(p->buf, "DHAV", 4) && memcmp(p->buf, "ZLAV", 4))
>          return 0;
> 
>      if (p->buf[4] == 0xf0 ||
> @@ -163,6 +163,19 @@ static int parse_ext(AVFormatContext *s, int
> length)
>      return 0;
>  }
> 
> +static int read_start_tag(AVIOContext *pb)
> +{
> +    unsigned int start_tag = avio_rl32(pb);
> +    return start_tag == MKTAG('D','H','A','V') || start_tag ==
> MKTAG('Z','L','A','V');
> +}
> +
> +static int read_end_tag(AVIOContext *pb)
> +{
> +    unsigned int end_tag = avio_rl32(pb);
> +    return end_tag == MKTAG('d','h','a','v') || end_tag ==
> MKTAG('z','l','a','v');
> +}
> +
> +
>  static int read_chunk(AVFormatContext *s)
>  {
>      DHAVContext *dhav = s->priv_data;
> @@ -173,11 +186,11 @@ static int read_chunk(AVFormatContext *s)
>      if (avio_feof(s->pb))
>          return AVERROR_EOF;
> 
> -    if (avio_rl32(s->pb) != MKTAG('D','H','A','V')) {
> +    if (!read_start_tag(s->pb)) {
>          dhav->last_good_pos += 0x8000;
>          avio_seek(s->pb, dhav->last_good_pos, SEEK_SET);
> 
> -        while (avio_rl32(s->pb) != MKTAG('D','H','A','V')) {
> +        while (!read_start_tag(s->pb)) {
>              if (avio_feof(s->pb))
>                  return AVERROR_EOF;
>              dhav->last_good_pos += 0x8000;
> @@ -247,7 +260,7 @@ static int64_t get_duration(AVFormatContext *s)
>          return 0;
> 
>      avio_seek(s->pb, avio_size(s->pb) - 8, SEEK_SET);
> -    if (avio_rl32(s->pb) == MKTAG('d','h','a','v')) {
> +    if (read_end_tag(s->pb)) {
>          int seek_back = avio_rl32(s->pb);
> 
>          avio_seek(s->pb, -seek_back, SEEK_CUR);
> @@ -281,12 +294,12 @@ static int dhav_read_header(AVFormatContext *s)
>          avio_skip(s->pb, 0x400 - 5);
>          dhav->last_good_pos = avio_tell(s->pb);
>      } else {
> -        if (!memcmp(signature, "DHAV", 4)) {
> +        if (!memcmp(signature, "DHAV", 4) || !memcmp(signature,
> "ZLAV", 4)) {
>              avio_seek(s->pb, -5, SEEK_CUR);
>              dhav->last_good_pos = avio_tell(s->pb);
>          } else if (s->pb->seekable) {
>              avio_seek(s->pb, avio_size(s->pb) - 8, SEEK_SET);
> -            while (avio_rl32(s->pb) == MKTAG('d','h','a','v')) {
> +            while (read_end_tag(s->pb)) {
>                  int seek_back;
> 
>                  seek_back = avio_rl32(s->pb) + 8;
> @@ -409,7 +422,7 @@ retry:
>      stream_index = dhav->type == 0xf0 ? dhav->audio_stream_index :
> dhav->video_stream_index;
>      if (stream_index < 0) {
>          avio_skip(s->pb, ret);
> -        if (avio_rl32(s->pb) == MKTAG('d','h','a','v'))
> +        if (read_end_tag(s->pb))
>              avio_skip(s->pb, 4);
>          goto retry;
>      }
> @@ -425,7 +438,7 @@ retry:
>      if (pkt->stream_index >= 0)
>          pkt->pts = get_pts(s, pkt->stream_index);
>      pkt->pos = dhav->last_good_pos;
> -    if (avio_rl32(s->pb) == MKTAG('d','h','a','v'))
> +    if (read_end_tag(s->pb))
>          avio_skip(s->pb, 4);
> 
>      return ret;
> diff --git a/libavformat/version.h b/libavformat/version.h
> index ddcca9ae50..b43193bcb1 100644
> --- a/libavformat/version.h
> +++ b/libavformat/version.h
> @@ -32,7 +32,7 @@
>  // Major bumping may affect Ticket5467, 5421, 5451(compatibility with
> Chromium)
>  // Also please add any ticket numbers that you believe might be
> affected here
>  #define LIBAVFORMAT_VERSION_MAJOR  58
> -#define LIBAVFORMAT_VERSION_MINOR  64
> +#define LIBAVFORMAT_VERSION_MINOR  65
>  #define LIBAVFORMAT_VERSION_MICRO 100
> 
>  #define LIBAVFORMAT_VERSION_INT
> AV_VERSION_INT(LIBAVFORMAT_VERSION_MAJOR, \
> --
> 2.25.1
> 
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