[FFmpeg-devel] [PATCH] avformat/mov: get the correct fragment stsd_id when decrypting the sample

[Zhao Zhili]

> From: Wang Yaqiang <wangyaqiang03 at kuaishou.com>
> 
> When determining whether a packet should be decrypted,
> should use the stsd_id of the fragment where the current packet is located.
> 
> Signed-off-by: Wang Yaqiang <wangyaqiang03 at kuaishou.com>
> ---
>  libavformat/isom.h | 1 +
>  libavformat/mov.c  | 7 ++++---
>  2 files changed, 5 insertions(+), 3 deletions(-)
> 
> diff --git a/libavformat/isom.h b/libavformat/isom.h
> index fd236b985f..64fb7065d5 100644
> --- a/libavformat/isom.h
> +++ b/libavformat/isom.h
> @@ -139,6 +139,7 @@ typedef struct MOVFragmentStreamInfo {
>      int index_base;
>      int index_entry;
>      MOVEncryptionIndex *encryption_index;
> +    int stsd_id; // current fragment stsd_id
>  } MOVFragmentStreamInfo;
> 
>  typedef struct MOVFragmentIndexItem {
> diff --git a/libavformat/mov.c b/libavformat/mov.c
> index 35e2271b14..a2c6a4f2a3 100644
> --- a/libavformat/mov.c
> +++ b/libavformat/mov.c
> @@ -4956,9 +4956,10 @@ static int mov_read_tfhd(MOVContext *c, AVIOContext *pb, MOVAtom atom)
>      av_log(c->fc, AV_LOG_TRACE, "frag flags 0x%x\n", frag->flags);
> 
>      frag_stream_info = get_current_frag_stream_info(&c->frag_index);
> -    if (frag_stream_info)
> +    if (frag_stream_info) {
>          frag_stream_info->next_trun_dts = AV_NOPTS_VALUE;
> -
> +        frag_stream_info->stsd_id = frag->stsd_id;
> +    }
>      return 0;
>  }
> 
> @@ -7223,7 +7224,7 @@ static int cenc_filter(MOVContext *mov, AVStream* st, MOVStreamContext *sc, AVPa
>      encryption_index = NULL;
>      if (frag_stream_info) {
>          // Note this only supports encryption info in the first sample descriptor.
> -        if (mov->fragment.stsd_id == 1) {
> +        if (frag_stream_info->stsd_id == 1) {
>              if (frag_stream_info->encryption_index) {
>                  encrypted_index = current_index - frag_stream_info->index_base;
>                  encryption_index = frag_stream_info->encryption_index;

LGTM.