[FFmpeg-devel] [PATCH] avformat/dashdec: accept and relay CENC decryption key

[Steven Liu]

Gyan Doshi <ffmpeg at gyani.pro> 于2022年5月14日周六 17:18写道：
>
> Allows to process CENC-encrypted media segments.
> Option arg syntax is same as that for option decryption_key in MOV demuxer
> ---
>  doc/demuxers.texi     | 11 +++++++++++
>  libavformat/dashdec.c |  5 +++++
>  2 files changed, 16 insertions(+)
>
> diff --git a/doc/demuxers.texi b/doc/demuxers.texi
> index 238b8e03a8..c95a9ae594 100644
> --- a/doc/demuxers.texi
> +++ b/doc/demuxers.texi
> @@ -274,6 +274,17 @@ which streams to actually receive.
>  Each stream mirrors the @code{id} and @code{bandwidth} properties from the
>  @code{<Representation>} as metadata keys named "id" and "variant_bitrate" respectively.
>
> + at subsection Options
> +
> +This demuxer accepts the following option:
> +
> + at table @option
> +
> + at item cenc_decryption_key
> +16-byte key, in hex, to decrypt files encrypted using ISO Common Encryption (CENC/AES-128 CTR; ISO/IEC 23001-7).
> +
> + at end table
> +
>  @section imf
>
>  Interoperable Master Format demuxer.
> diff --git a/libavformat/dashdec.c b/libavformat/dashdec.c
> index 0b5ff5aeb9..0f66251354 100644
> --- a/libavformat/dashdec.c
> +++ b/libavformat/dashdec.c
> @@ -150,6 +150,7 @@ typedef struct DASHContext {
>      char *allowed_extensions;
>      AVDictionary *avio_opts;
>      int max_url_size;
> +    char *cenc_decryption_key;
>
>      /* Flags for init section*/
>      int is_init_section_common_video;
> @@ -1893,6 +1894,9 @@ static int reopen_demux_for_component(AVFormatContext *s, struct representation
>      pls->ctx->pb = &pls->pb.pub;
>      pls->ctx->io_open  = nested_io_open;
>
> +    if (c->cenc_decryption_key)
> +        av_dict_set(&in_fmt_opts, "decryption_key", c->cenc_decryption_key, AV_OPT_FLAG_DECODING_PARAM);
> +
>      // provide additional information from mpd if available
>      ret = avformat_open_input(&pls->ctx, "", in_fmt, &in_fmt_opts); //pls->init_section->url
>      av_dict_free(&in_fmt_opts);
> @@ -2344,6 +2348,7 @@ static const AVOption dash_options[] = {
>          OFFSET(allowed_extensions), AV_OPT_TYPE_STRING,
>          {.str = "aac,m4a,m4s,m4v,mov,mp4,webm,ts"},
>          INT_MIN, INT_MAX, FLAGS},
> +    { "cenc_decryption_key", "Media decryption key (hex)", OFFSET(cenc_decryption_key), AV_OPT_TYPE_STRING, {.str = NULL}, INT_MIN, INT_MAX, .flags = FLAGS },
>      {NULL}
>  };
>
> --
> 2.36.1
>
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LGTM

Thanks