On Sun, 29 Jan 2017 19:56:39 +0000
Mark Thompson <[email protected]> wrote:
> For use by codec implementations which can allocate frames internally.
> ---
> doc/APIchanges | 3 +++
> libavcodec/avcodec.h | 47 +++++++++++++++++++++++++++++++++++++++++++++--
> libavcodec/utils.c | 1 +
> libavcodec/version.h | 2 +-
> 4 files changed, 50 insertions(+), 3 deletions(-)
>
> diff --git a/doc/APIchanges b/doc/APIchanges
> index c8c2a219f..59d7549d1 100644
> --- a/doc/APIchanges
> +++ b/doc/APIchanges
> @@ -13,6 +13,9 @@ libavutil: 2015-08-28
>
> API changes, most recent first:
>
> +2017-xx-xx - xxxxxxx - lavc 57.32.0 - avcodec.h
> + Add AVCodecContext.hw_device_ctx.
> +
> 2016-xx-xx - xxxxxxx - lavc 57.31.0 - avcodec.h
> Add AVCodecContext.apply_cropping to control whether cropping
> is handled by libavcodec or the caller.
> diff --git a/libavcodec/avcodec.h b/libavcodec/avcodec.h
> index 18721561d..e7f9ec711 100644
> --- a/libavcodec/avcodec.h
> +++ b/libavcodec/avcodec.h
> @@ -3092,8 +3092,14 @@ typedef struct AVCodecContext {
>
> /**
> * A reference to the AVHWFramesContext describing the input (for
> encoding)
> - * or output (decoding) frames. The reference is set by the caller and
> - * afterwards owned (and freed) by libavcodec.
> + * or output (for decoding) frames which will be used by a hardware
> codec.
> + *
> + * It can be set by the user if they wish to supply the frames used, or
> it
> + * can be set automatically by libavcodec for decoding when get_format()
> + * indicates that it should output hardware frames. If supplied by the
> + * user, the reference is thereafter owned (and freed) by libavcodec.
> + *
> + * If set by the user:
> *
> * - decoding: This field should be set by the caller from the
> get_format()
> * callback. The previous reference (if any) will always be
> @@ -3110,6 +3116,20 @@ typedef struct AVCodecContext {
> * AVCodecContext.pix_fmt.
> *
> * This field should be set before avcodec_open2() is called.
> + *
> + * If set by libavcodec:
> + *
> + * - decoding: The hw_device_ctx field should be set by the user before
> + * calling avcodec_open2(). If at some later point a
> hardware
> + * pixel format is selected by get_format(), then a new
> + * AVHWFramesContext will be created by the decoder and put
> + * in this field.
> + *
> + * It can be read only inside the get_buffer2() callback
> + * (which must return a buffer from the given context).
Any reason for this specific restriction?
Shouldn't it be ok to access it any time - just that it might not be
set to something useful? (Could be NULL or wrong format.)
> + *
> + * - encoding: Unused. In this case the user must not supply hardware
> + * frames to the encoder.
> */
> AVBufferRef *hw_frames_ctx;
>
> @@ -3139,6 +3159,29 @@ typedef struct AVCodecContext {
> * (with the display dimensions being determined by the crop_* fields).
> */
> int apply_cropping;
> +
> + /**
> + * A reference to the AVHWDeviceContext describing the device which will
> + * be used by a hardware encoder/decoder. The reference is set by the
> + * caller and afterwards owned (and freed) by libavcodec.
> + *
> + * This should only be used if either the codec device does not require
> + * hardware frames or any that are used are allocated internally by
> + * libavcodec. If the frames may be supplied by the user, then
> + * hw_frames_ctx must be used instead.
I'm not sure about the word "may". For some decoders, the user can
either set hw_device_ctx, or he can set a hw_frames_ctx (but they
can't both be set). Some decoders support hw_frames_ctx only. Shouldn't
it say "have to" instead of "may"? Maybe the wording is fine - I'm not a
native speaker.
> + *
> + * If the same device is to be used throughout the lifetime of a decoder,
> + * this field should be set before avcodec_open2() is called. Some
> + * decoders can only use one device and therefore require this behaviour.
> + *
> + * For other decoders, the hw_device_ctx field can be set inside the
> + * get_format() callback to indicate the device to use for decoding a
> + * particular section of the stream. Any previous value in the field
> + * must be unreferenced before being overwritten. This also supports
> + * changing between use of hw_device_ctx and hw_frames_ctx - when doing
> + * so, the other field must always be set to NULL.
> + */
> + AVBufferRef *hw_device_ctx;
> } AVCodecContext;
>
> /**
> diff --git a/libavcodec/utils.c b/libavcodec/utils.c
> index 2978109a2..1d316bd03 100644
> --- a/libavcodec/utils.c
> +++ b/libavcodec/utils.c
> @@ -801,6 +801,7 @@ av_cold int avcodec_close(AVCodecContext *avctx)
> avctx->nb_coded_side_data = 0;
>
> av_buffer_unref(&avctx->hw_frames_ctx);
> + av_buffer_unref(&avctx->hw_device_ctx);
>
> if (avctx->priv_data && avctx->codec && avctx->codec->priv_class)
> av_opt_free(avctx->priv_data);
> diff --git a/libavcodec/version.h b/libavcodec/version.h
> index df0c01f4c..271bc9d6b 100644
> --- a/libavcodec/version.h
> +++ b/libavcodec/version.h
> @@ -28,7 +28,7 @@
> #include "libavutil/version.h"
>
> #define LIBAVCODEC_VERSION_MAJOR 57
> -#define LIBAVCODEC_VERSION_MINOR 31
> +#define LIBAVCODEC_VERSION_MINOR 32
> #define LIBAVCODEC_VERSION_MICRO 0
>
> #define LIBAVCODEC_VERSION_INT AV_VERSION_INT(LIBAVCODEC_VERSION_MAJOR, \
Otherwise LGTM.
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