[FFmpeg-devel] [PATCH] lavc/tta: Add support for encrypted streams

[Paul B Mahol]

On 1/29/13, James Almer <jamrial at gmail.com> wrote:
>
> Signed-off-by: James Almer <jamrial at gmail.com>
> ---
>  libavcodec/tta.c     | 51
> +++++++++++++++++++++++++++++++++++++++++++++++----
>  libavcodec/version.h |  2 +-
>  2 files changed, 48 insertions(+), 5 deletions(-)
>
> diff --git a/libavcodec/tta.c b/libavcodec/tta.c
> index fb793be..a42a6d7 100644
> --- a/libavcodec/tta.c
> +++ b/libavcodec/tta.c
> @@ -34,6 +34,8 @@
>  #include "get_bits.h"
>  #include "internal.h"
>  #include "libavutil/crc.h"
> +#include "libavutil/intreadwrite.h"
> +#include "libavutil/opt.h"
>
>  #define FORMAT_SIMPLE    1
>  #define FORMAT_ENCRYPTED 2
> @@ -57,6 +59,7 @@ typedef struct TTAChannel {
>  } TTAChannel;
>
>  typedef struct TTAContext {
> +    const AVClass *tta_decoder_class;

Is there reason to have such long name?

>      AVCodecContext *avctx;
>      AVFrame frame;
>      GetBitContext gb;
> @@ -68,6 +71,8 @@ typedef struct TTAContext {
>
>      int32_t *decode_buffer;
>
> +    uint8_t crc_pass[8];
> +    uint8_t *pass;
>      TTAChannel *ch_ctx;
>  } TTAContext;
>
> @@ -93,8 +98,13 @@ static const int32_t ttafilter_configs[4] = {
>      12
>  };
>
> -static void ttafilter_init(TTAFilter *c, int32_t shift) {
> +static void ttafilter_init(TTAContext *s, TTAFilter *c, int32_t shift) {
>      memset(c, 0, sizeof(TTAFilter));
> +    if (s->pass) {
> +        int i;
> +        for(i = 0; i < 8; i++)

Please have consistent style: whitespace is missing between for and (

> +            c->qm[i] = sign_extend(s->crc_pass[i], 8);
> +    }
>      c->shift = shift;
>     c->round = shift_1[shift-1];
>  //    c->round = 1 << (shift - 1);
> @@ -173,6 +183,21 @@ static int tta_check_crc(TTAContext *s, const uint8_t
> *buf, int buf_size)
>      return 0;
>  }
>
> +static uint64_t tta_check_crc64(uint8_t *pass)
> +{
> +    uint64_t crc = UINT64_MAX, poly = 0x42F0E1EBA9EA3693U;
> +    uint8_t *end = pass + sizeof(pass);
> +    int i;
> +
> +    while (pass < end){
> +        crc ^= (uint64_t)*pass++ << 56;
> +        for (i = 0; i < 8; i++)
> +            crc = (crc << 1) ^ (poly & (((int64_t) crc) >> 63));
> +    }
> +
> +    return av_bswap64(crc) ^ UINT64_MAX;
> +}
> +
>  static av_cold int tta_decode_init(AVCodecContext * avctx)
>  {
>      TTAContext *s = avctx->priv_data;
> @@ -201,8 +226,11 @@ static av_cold int tta_decode_init(AVCodecContext *
> avctx)
>              return AVERROR_INVALIDDATA;
>          }
>          if (s->format == FORMAT_ENCRYPTED) {
> -            av_log_missing_feature(avctx, "Encrypted TTA", 0);
> -            return AVERROR_PATCHWELCOME;
> +            if (!s->pass) {
> +                av_log(avctx, AV_LOG_ERROR, "Missing password for encrypted
> stream. Please use the -password option\n");
> +                return AVERROR(EINVAL);
> +            }
> +            AV_WB64(s->crc_pass, tta_check_crc64(s->pass));
>          }
>          avctx->channels = s->channels = get_bits(&s->gb, 16);
>          if (s->channels > 1 && s->channels < 9)
> @@ -321,7 +349,7 @@ static int tta_decode_frame(AVCodecContext *avctx, void
> *data,
>      // init per channel states
>      for (i = 0; i < s->channels; i++) {
>          s->ch_ctx[i].predictor = 0;
> -        ttafilter_init(&s->ch_ctx[i].filter, ttafilter_configs[s->bps-1]);
> +        ttafilter_init(s, &s->ch_ctx[i].filter,
> ttafilter_configs[s->bps-1]);
>          rice_init(&s->ch_ctx[i].rice, 10, 10);
>      }
>
> @@ -465,6 +493,20 @@ static av_cold int tta_decode_close(AVCodecContext
> *avctx) {
>      return 0;
>  }
>
> +#define OFFSET(x) offsetof(TTAContext, x)
> +#define DEC (AV_OPT_FLAG_DECODING_PARAM | AV_OPT_FLAG_AUDIO_PARAM)
> +static const AVOption options[] = {
> +    { "password", "Set decoding password", OFFSET(pass),
> AV_OPT_TYPE_STRING, { .str = NULL }, 0, 0, DEC },
> +    { NULL },
> +};
> +
> +static const AVClass tta_decoder_class = {
> +    .class_name = "TTA Decoder",
> +    .item_name  = av_default_item_name,
> +    .option     = options,
> +    .version    = LIBAVUTIL_VERSION_INT,
> +};
> +
>  AVCodec ff_tta_decoder = {
>      .name           = "tta",
>      .type           = AVMEDIA_TYPE_AUDIO,
> @@ -475,4 +517,5 @@ AVCodec ff_tta_decoder = {
>      .decode         = tta_decode_frame,
>      .capabilities   = CODEC_CAP_DR1,
>      .long_name      = NULL_IF_CONFIG_SMALL("TTA (True Audio)"),
> +    .priv_class     = &tta_decoder_class,
>  };
> diff --git a/libavcodec/version.h b/libavcodec/version.h
> index 3f69494..01ce0ea 100644
> --- a/libavcodec/version.h
> +++ b/libavcodec/version.h
> @@ -30,7 +30,7 @@
>
>  #define LIBAVCODEC_VERSION_MAJOR 54
>  #define LIBAVCODEC_VERSION_MINOR 91
> -#define LIBAVCODEC_VERSION_MICRO 100
> +#define LIBAVCODEC_VERSION_MICRO 101
>
>  #define LIBAVCODEC_VERSION_INT  AV_VERSION_INT(LIBAVCODEC_VERSION_MAJOR, \
>                                                 LIBAVCODEC_VERSION_MINOR, \
> --
> 1.7.12.4
>
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