[FFmpeg-devel] [PATCH 1/3 v2] lavu: Add AVSphericalMapping type and frame side data

[James Almer]

On 11/15/2016 10:39 PM, Michael Niedermayer wrote:
> On Tue, Nov 15, 2016 at 11:56:48AM -0500, Vittorio Giovara wrote:
> [...]
>> +/**
>> + * This structure describes how to handle spherical videos, outlining
>> + * information about projection, initial layout, and any other view modifier.
>> + *
>> + * @note The struct must be allocated with av_spherical_alloc() and
>> + *       its size is not a part of the public ABI.
>> + */
>> +typedef struct AVSphericalMapping {
>> +    /**
>> +     * Projection type.
>> +     */
>> +    enum AVSphericalProjection projection;
>> +
>> +    /**
>> +     * @name Initial orientation
>> +     * @{
>> +     * These fields represent the pose values that measure the rotation
>> +     * transformation (in degrees) to be applied to the projection.
> 
>> +     * They are exported as 16.16 fixed point.
> 
> why waste 7 bits of precission ?

16.16 seems to be part of the spec

https://github.com/google/spatial-media/blob/master/docs/spherical-video-v2-rfc.md

> 
> something like
> value * 180.0 / INT32_MAX
> seems simpler
> the user can also then just do
> value * PI / INT32_MAX
> to get radians instead of degree
> (or similar with 360 and UINT32_MAX)
> 
> 
> 
> [...]
> 
> 
> 
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