[FFmpeg-devel] [PATCH 1/2] vp9: add support for resolution changes in inter frames.

[James Almer]

On 22/04/15 12:20 AM, James Almer wrote:
> On 21/04/15 9:54 PM, Ronald S. Bultje wrote:
>> ---
>>  libavcodec/vp9.c             | 316 ++++++++++++++++++++++---------------------
>>  libavcodec/vp9_mc_template.c | 171 +++++++++++++++++++++++
>>  libavcodec/vp9_parser.c      |   5 +-
>>  libavcodec/vp9dsp.c          | 205 ++++++++++++++++++++++++++--
>>  libavcodec/vp9dsp.h          |   9 ++
>>  5 files changed, 535 insertions(+), 171 deletions(-)
>>  create mode 100644 libavcodec/vp9_mc_template.c
>>
>> diff --git a/libavcodec/vp9.c b/libavcodec/vp9.c
>> index 89257fa..ee73325 100644
>> --- a/libavcodec/vp9.c
>> +++ b/libavcodec/vp9.c
>> @@ -242,7 +242,7 @@ typedef struct VP9Context {
>>      // whole-frame cache
>>      uint8_t *intra_pred_data[3];
>>      struct VP9Filter *lflvl;
>> -    DECLARE_ALIGNED(32, uint8_t, edge_emu_buffer)[71*80];
>> +    DECLARE_ALIGNED(32, uint8_t, edge_emu_buffer)[135*144];
>>  
>>      // block reconstruction intermediates
>>      int block_alloc_using_2pass;
>> @@ -251,6 +251,8 @@ typedef struct VP9Context {
>>      struct { int x, y; } min_mv, max_mv;
>>      DECLARE_ALIGNED(32, uint8_t, tmp_y)[64*64];
>>      DECLARE_ALIGNED(32, uint8_t, tmp_uv)[2][32*32];
>> +    uint16_t mvscale[3][2];
>> +    uint8_t mvstep[3][2];
>>  } VP9Context;
>>  
>>  static const uint8_t bwh_tab[2][N_BS_SIZES][2] = {
>> @@ -577,6 +579,26 @@ static int decode_frame_header(AVCodecContext *ctx,
>>                      s->varcompref[1] = 2;
>>                  }
>>              }
>> +
>> +            for (i = 0; i < 3; i++) {
>> +                AVFrame *ref = s->refs[s->refidx[i]].f;
>> +                int refw = ref->width, refh = ref->height;
>> +
>> +                if (refw == w && refh == h) {
>> +                    s->mvscale[i][0] = s->mvscale[i][1] = 0;
>> +                } else {
>> +                    if (w * 2 < refw || h * 2 < refh || w > 16 * refw || h > 16 * refh) {
>> +                        av_log(ctx, AV_LOG_ERROR,
>> +                               "Invalid ref frame dimensions %dx%d for frame size %dx%d\n",
>> +                               refw, refh, w, h);
>> +                        return AVERROR_INVALIDDATA;
>> +                    }
>> +                    s->mvscale[i][0] = (refw << 14) / w;
>> +                    s->mvscale[i][1] = (refh << 14) / h;
>> +                    s->mvstep[i][0] = 16 * s->mvscale[i][0] >> 14;
>> +                    s->mvstep[i][1] = 16 * s->mvscale[i][1] >> 14;
>> +                }
>> +            }
>>          }
>>      }
>>      s->refreshctx   = s->errorres ? 0 : get_bits1(&s->gb);
>> @@ -2524,12 +2546,118 @@ static void intra_recon(AVCodecContext *ctx, ptrdiff_t y_off, ptrdiff_t uv_off)
>>      }
>>  }
>>  
>> -static av_always_inline void mc_luma_dir(VP9Context *s, vp9_mc_func (*mc)[2],
>> -                                         uint8_t *dst, ptrdiff_t dst_stride,
>> -                                         const uint8_t *ref, ptrdiff_t ref_stride,
>> -                                         ThreadFrame *ref_frame,
>> -                                         ptrdiff_t y, ptrdiff_t x, const VP56mv *mv,
>> -                                         int bw, int bh, int w, int h)
>> +static av_always_inline void mc_luma_scaled(VP9Context *s, vp9_scaled_mc_func smc,
>> +                                            uint8_t *dst, ptrdiff_t dst_stride,
>> +                                            const uint8_t *ref, ptrdiff_t ref_stride,
>> +                                            ThreadFrame *ref_frame,
>> +                                            ptrdiff_t y, ptrdiff_t x, const VP56mv *mv,
>> +                                            int bw, int bh, int w, int h,
>> +                                            const uint16_t *scale, const uint8_t *step)
>> +{
>> +#define scale_mv(n, dim) (((int64_t)n * scale[dim]) >> 14)
>> +    // BUG libvpx seems to scale the two components separately. This introduces
>> +    // rounding errors but we have to reproduce them to be exactly compatible
>> +    // with the output from libvpx...
> 
> Did you report it to libvpx? It's probably a better idea to fix the bug in the reference
> library than purposely reproduce the buggy behavior in our implementation to remain
> compatible.

Just checked the link further down the patch (As i should have done before replying).
Assuming it's the same bug as this one then forget what i said, they decided to leave
the bitstream unchanged.