[FFmpeg-devel] [PATCH 1/4] libavcodec/adts_header: add frame_length field and avpriv function to parse AAC ADTS header

[Steven Liu]

> 2021年8月16日 上午2:25，Nachiket Tarate <nachiket.programmer at gmail.com> 写道：
> 
> These will be used by HLS demuxer in case of sample decryption.
> 
> Signed-off-by: Nachiket Tarate <nachiket.programmer at gmail.com>
> ---
> libavcodec/adts_header.c |  1 +
> libavcodec/adts_header.h | 14 ++++++++++++++
> libavcodec/adts_parser.c | 32 ++++++++++++++++++++++++++++++++
> 3 files changed, 47 insertions(+)
> 
> diff --git a/libavcodec/adts_header.c b/libavcodec/adts_header.c
> index 0889820f8a..e4454529c4 100644
> --- a/libavcodec/adts_header.c
> +++ b/libavcodec/adts_header.c
> @@ -66,6 +66,7 @@ int ff_adts_header_parse(GetBitContext *gbc, AACADTSHeaderInfo *hdr)
>     hdr->sample_rate    = avpriv_mpeg4audio_sample_rates[sr];
>     hdr->samples        = (rdb + 1) * 1024;
>     hdr->bit_rate       = size * 8 * hdr->sample_rate / hdr->samples;
> +    hdr->frame_length   = size;
> 
>     return size;
> }
> diff --git a/libavcodec/adts_header.h b/libavcodec/adts_header.h
> index f615f6a9f9..9ecd67fb5b 100644
> --- a/libavcodec/adts_header.h
> +++ b/libavcodec/adts_header.h
> @@ -34,6 +34,7 @@ typedef struct AACADTSHeaderInfo {
>     uint8_t  sampling_index;
>     uint8_t  chan_config;
>     uint8_t  num_aac_frames;
> +    uint32_t frame_length;
> } AACADTSHeaderInfo;
> 
> /**
> @@ -47,4 +48,17 @@ typedef struct AACADTSHeaderInfo {
>  */
> int ff_adts_header_parse(GetBitContext *gbc, AACADTSHeaderInfo *hdr);
> 
> +/**
> + * Parse the ADTS frame header contained in the buffer, which is
> + * the first 54 bits.
> + * @param[in]  buf  Pointer to buffer containing the first 54 bits of the frame.
> + * @param[in]  size Size of buffer containing the first 54 bits of the frame.
> + * @param[out] phdr Pointer to pointer to struct AACADTSHeaderInfo for which
> + * memory is allocated and header info is written into it.
> + * @return Returns 0 on success, -1 if there is a sync word mismatch,
> + * -2 if the version element is invalid, -3 if the sample rate
> + * element is invalid, or -4 if the bit rate element is invalid.
> + */
> +int avpriv_adts_header_parse(AACADTSHeaderInfo **phdr, const uint8_t *buf, size_t size);
> +
> #endif /* AVCODEC_ADTS_HEADER_H */
> diff --git a/libavcodec/adts_parser.c b/libavcodec/adts_parser.c
> index 5c9f8ff6f2..32489dadf4 100644
> --- a/libavcodec/adts_parser.c
> +++ b/libavcodec/adts_parser.c
> @@ -42,3 +42,35 @@ int av_adts_header_parse(const uint8_t *buf, uint32_t *samples, uint8_t *frames)
>     return AVERROR(ENOSYS);
> #endif
> }
> +
> +int avpriv_adts_header_parse(AACADTSHeaderInfo **phdr, const uint8_t *buf, size_t size)
> +{
> +#if CONFIG_ADTS_HEADER
> +    int ret = 0;
> +    GetBitContext gb;
> +
> +    if (size < AV_AAC_ADTS_HEADER_SIZE)
> +        return AVERROR_INVALIDDATA;
> +
> +    if (!*phdr)
> +        *phdr = av_mallocz(sizeof(AACADTSHeaderInfo));
> +    if (!*phdr)
> +        return AVERROR(ENOMEM);
> +
> +    ret = init_get_bits8(&gb, buf, AV_AAC_ADTS_HEADER_SIZE);
> +    if (ret < 0) {
> +        av_free(*phdr);
> +        return ret;
> +    }
> +
> +    ret = ff_adts_header_parse(&gb, *phdr);
> +    if (ret < 0) {
> +        av_free(*phdr);
> +        return ret;
> +    }
> +
> +    return 0;
> +#else
> +    return AVERROR(ENOSYS);
> +#endif
> +}
> -- 
> 2.17.1
> 
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> 

Looks ok to me, will fix some code style problem locally and push one week after if there have no objections.

Thanks

Steven Liu