[vlc-devel] [PATCH] lua: Expose media tracks through lua bindings

[Hugo Beauzée-Luyssen]

On 01/02/2017 06:01 PM, Rémi Denis-Courmont wrote:
> Le lundi 2 janvier 2017, 16:31:21 Hugo Beauzée-Luyssen a écrit :
>> ---
>>  modules/lua/libs/input.c | 123
>> ++++++++++++++++++++++++++++++++++++++++++++++- share/lua/README.txt     |
>> 28 +++++++++++
>>  2 files changed, 150 insertions(+), 1 deletion(-)
>>
>> diff --git a/modules/lua/libs/input.c b/modules/lua/libs/input.c
>> index 6d14ebce78..9fd49dbc36 100644
>> --- a/modules/lua/libs/input.c
>> +++ b/modules/lua/libs/input.c
>> @@ -382,6 +382,127 @@ static int vlclua_input_item_set_meta( lua_State *L )
>>      return 1;
>>  }
>>
>> +#define PUSH_INT( val, name ) \
>> +    lua_pushinteger( L, val ); \
>> +    lua_setfield( L, -2, name );
>> +
>> +#define PUSH_STR( val, name ) \
>> +    lua_pushstring( L, val ); \
>> +    lua_setfield( L, -2, name );
>> +
>> +#define PUSH_NUM( val, name ) \
>> +    lua_pushnumber( L, val ); \
>> +    lua_setfield( L, -2, name );
>> +
>> +static const char* orientation_to_str(video_orientation_t orient)
>> +{
>> +    switch (orient)
>> +    {
>> +    case ORIENT_TOP_LEFT:
>> +        return "topleft";
>> +    case ORIENT_TOP_RIGHT:
>> +        return "topright";
>> +    case ORIENT_BOTTOM_LEFT:
>> +        return "bottomleft";
>> +    case ORIENT_BOTTOM_RIGHT:
>> +        return "bottomright";
>> +    case ORIENT_LEFT_TOP:
>> +        return "lefttop";
>> +    case ORIENT_LEFT_BOTTOM:
>> +        return "leftbottom";
>> +    case ORIENT_RIGHT_TOP:
>> +        return "righttop";
>> +    case ORIENT_RIGHT_BOTTOM:
>> +        return "rightbottom";
>> +    default:
>> +        vlc_assert_unreachable();
>> +    }
>> +}
>> +
>> +static const char* projection_to_str(video_projection_mode_t proj)
>> +{
>> +    switch (proj)
>> +    {
>> +    case PROJECTION_MODE_RECTANGULAR:
>> +        return "rectangular";
>> +    case PROJECTION_MODE_EQUIRECTANGULAR:
>> +        return "equirectangular";
>> +    case PROJECTION_MODE_CUBEMAP_LAYOUT_STANDARD:
>> +        return "cubemap";
>> +    default:
>> +        vlc_assert_unreachable();
>> +    }
>> +}
>> +
>> +static int vlclua_input_item_tracks( lua_State *L )
>> +{
>> +    input_item_t *p_item = vlclua_input_item_get_internal( L );
>> +    lua_newtable( L );
>> +
>> +    vlc_mutex_lock( &p_item->lock );
>> +    for ( int i = 0; i < p_item->i_es; ++i )
>> +    {
>> +        const es_format_t* p_es = p_item->es[i];
>> +
>> +        lua_newtable( L );
>> +
>> +        lua_pushlstring( L, (const char*)&p_es->i_codec, 4 );
>> +        lua_setfield( L, -2, "codec" );
>> +        lua_pushlstring( L, (const char*)&p_es->i_original_fourcc, 4 );
>> +        lua_setfield( L, -2, "original_fourcc" );
>> +        PUSH_INT( p_es->i_id, "id" );
>
> In general I consider ES signed integer IDs as broken by design, and I am not
> very keen on exposing them any further than backward compatibility requires.
>
> Can't we have proper a Lua object per ES, not expose the ID to Lua code and
> limit the use of IDs to the back-end? Then we can fix the implementation later
> without breaking Lua scripts.

I guess it's doable, but I was mostly trying to have something that 
mimics libvlc. I'll check what can be done for that

>
> (On top of my head, the ID is really only useful to select a track as of now.)
>

That's exactly the use case here.

>
>> +        PUSH_INT( p_es->i_profile, "profile" );
>> +        PUSH_INT( p_es->i_level, "level" );
>> +        PUSH_INT( p_es->i_bitrate, "bitrate" );
>> +        PUSH_STR( p_es->psz_language, "language" );
>> +        PUSH_STR( p_es->psz_description, "description" );
>