Re: [FFmpeg-devel] [PATCH] libavformat/usmdec: add support for HCA stream decryption

[Andreas Rheinhardt <andreas.rheinhardt@outlook.com>]

Pavel Roslyy:
> ---
>  libavformat/usmdec.c | 53 +++++++++++++++++++++++++++++++++++++++++---
>  1 file changed, 50 insertions(+), 3 deletions(-)
> 
> diff --git a/libavformat/usmdec.c b/libavformat/usmdec.c
> index fd28e935ce..c5f2e208df 100644
> --- a/libavformat/usmdec.c
> +++ b/libavformat/usmdec.c
> @@ -19,6 +19,7 @@
>   * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
>   */
>  
> +#include "libavutil/opt.h"
>  #include "libavutil/intfloat.h"
>  #include "libavutil/intreadwrite.h"
>  #include "libavutil/mem.h"
> @@ -47,10 +48,14 @@ typedef struct USMChannel {
>  } USMChannel;
>  
>  typedef struct USMDemuxContext {
> +    const AVClass *class;
>      USMChannel ch[4][256];
>      int nb_channels[4];
>      uint8_t *header;
>      unsigned header_size;
> +    int64_t hca_keyl;
> +    int64_t hca_keyh;
> +    int hca_subkey;
>  } USMDemuxContext;
>  
>  static int usm_probe(const AVProbeData *p)
> @@ -314,6 +319,7 @@ static int64_t parse_chunk(AVFormatContext *s, AVIOContext *pb,
>                      par->sample_rate = ch->rate.num;
>                      par->ch_layout.nb_channels = ch->nb_channels;
>                      st->duration = ch->duration;
> +                    get_extradata = 1;
>                      break;
>                  }
>  
> @@ -323,7 +329,6 @@ static int64_t parse_chunk(AVFormatContext *s, AVIOContext *pb,
>                  avpriv_set_pts_info(st, 64, ch->rate.den, ch->rate.num);
>  
>                  ffstream(st)->need_parsing = AVSTREAM_PARSE_TIMESTAMPS;
> -                get_extradata = ch->codec_id == AV_CODEC_ID_ADPCM_ADX;
>                  ch->extradata_pos = avio_tell(pb);
>              }
>  
> @@ -333,10 +338,29 @@ static int64_t parse_chunk(AVFormatContext *s, AVIOContext *pb,
>  
>              pkt_size = chunk_size - (ret - chunk_start) - padding_size;
>              if (get_extradata) {
> -                if ((ret = ff_get_extradata(s, st->codecpar, pb, pkt_size)) < 0)
> +                AVCodecParameters *par;
> +                par = st->codecpar;
> +
> +                // HCA decoder expects last 10 bytes to contain decryption keys
> +                int key_buf = ch->codec_id == AV_CODEC_ID_HCA ? 10 : 0;
> +                ret = ff_alloc_extradata(par, pkt_size + key_buf);
> +                if (ret < 0)
>                      return ret;
> +
> +                ret = avio_read(pb, par->extradata, pkt_size);
> +                if (ret < pkt_size) {
> +                    av_freep(&par->extradata);
> +                    par->extradata_size = 0;
> +                    return AVERROR(EIO);
> +                }
> +
> +                if (ch->codec_id == AV_CODEC_ID_HCA) {
> +                    AV_WB32(par->extradata + par->extradata_size - 10, usm->hca_keyh);
> +                    AV_WB32(par->extradata + par->extradata_size -  6, usm->hca_keyl);
> +                    AV_WB16(par->extradata + par->extradata_size -  2, usm->hca_subkey);
> +                }
>              } else {
> -                if (ret == ch->extradata_pos && ch->codec_id == AV_CODEC_ID_ADPCM_ADX) {
> +                if (ret == ch->extradata_pos && ch->type == AVMEDIA_TYPE_AUDIO) {
>                      avio_skip(pb, pkt_size);
>                      ret = 0;
>                  } else {
> @@ -416,10 +440,33 @@ static int usm_read_close(AVFormatContext *s)
>      return 0;
>  }
>  
> +#define OFFSET(x) offsetof(USMDemuxContext, x)
> +#define FLAGS AV_OPT_FLAG_AUDIO_PARAM | AV_OPT_FLAG_DECODING_PARAM
> +static const AVOption usm_options[] = {
> +    { "hca_lowkey",
> +        "Low key used for handling CRI HCA streams", OFFSET(hca_keyl),
> +        AV_OPT_TYPE_INT64, {.i64=0}, .min = 0, .max = UINT32_MAX, .flags = FLAGS, },
> +    { "hca_highkey",
> +        "High key used for handling CRI HCA streams", OFFSET(hca_keyh),
> +        AV_OPT_TYPE_INT64, {.i64=0}, .min = 0, .max = UINT32_MAX, .flags = FLAGS, },

Why are these two options instead of one? The HCA decoder also treats it
as 64bit value.

> +    { "hca_subkey",
> +        "Subkey used for handling CRI HCA streams", OFFSET(hca_subkey),
> +        AV_OPT_TYPE_INT, {.i64=0}, .min = 0, .max = UINT16_MAX, .flags = FLAGS },
> +    { NULL },
> +};
> +
> +static const AVClass usm_class = {
> +    .class_name = "usm",
> +    .item_name  = av_default_item_name,
> +    .option     = usm_options,
> +    .version    = LIBAVUTIL_VERSION_INT,
> +};
> +
>  const FFInputFormat ff_usm_demuxer = {
>      .p.name         = "usm",
>      .p.long_name    = NULL_IF_CONFIG_SMALL("CRI USM"),
>      .p.extensions   = "usm",
> +    .p.priv_class   = &usm_class,
>      .p.flags        = AVFMT_GENERIC_INDEX | AVFMT_NO_BYTE_SEEK | AVFMT_NOBINSEARCH,
>      .priv_data_size = sizeof(USMDemuxContext),
>      .read_probe     = usm_probe,

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