[FFmpeg-devel] [PATCH 5/5] ffmpeg: Add {h, v}scale argument to display_matrix option to allow for scaling via the display matrix
Andreas Rheinhardt
andreas.rheinhardt at outlook.com
Tue Aug 16 20:26:49 EEST 2022
Thilo Borgmann:
> ---
> doc/ffmpeg.texi | 4 ++++
> fftools/ffmpeg_filter.c | 15 +++++++++++++++
> fftools/ffmpeg_opt.c | 10 ++++++++++
> libavutil/display.c | 21 +++++++++++++++++++++
> libavutil/display.h | 28 ++++++++++++++++++++++++++++
> 5 files changed, 78 insertions(+)
>
> diff --git a/doc/ffmpeg.texi b/doc/ffmpeg.texi
> index 5d3e3b3052..52cca7a407 100644
> --- a/doc/ffmpeg.texi
> +++ b/doc/ffmpeg.texi
> @@ -923,6 +923,10 @@ The @code{-autorotate} logic will be affected.
> @item hflip=@var{[0,1]}
> @item vflip=@var{[0,1]}
> Set a horizontal or vertical flip.
> + at item hscale=@var{[0,2]}
> +Set a horizontal scaling by factor of the given floating-point value.
> + at item vscale=@var{[0,2]}
> +Set a vertical scaling by factor of the given floating-point value.
> @end table
>
> @item -vn (@emph{input/output})
> diff --git a/fftools/ffmpeg_filter.c b/fftools/ffmpeg_filter.c
> index f9ae76f76d..0759c08687 100644
> --- a/fftools/ffmpeg_filter.c
> +++ b/fftools/ffmpeg_filter.c
> @@ -778,9 +778,24 @@ static int configure_input_video_filter(FilterGraph *fg, InputFilter *ifilter,
> if (ist->autorotate && !(desc->flags & AV_PIX_FMT_FLAG_HWACCEL)) {
> int32_t *displaymatrix = ifilter->displaymatrix;
> double theta;
> + double hscale = 1.0f;
> + double vscale = 1.0f;
>
> if (!displaymatrix)
> displaymatrix = (int32_t *)av_stream_get_side_data(ist->st, AV_PKT_DATA_DISPLAYMATRIX, NULL);
> +
> + if (displaymatrix) {
> + hscale = av_display_hscale_get(displaymatrix);
> + vscale = av_display_vscale_get(displaymatrix);
> +
> + if (hscale != 1.0f || vscale != 1.0f) {
> + char scale_buf[128];
> + snprintf(scale_buf, sizeof(scale_buf), "%f*iw:%f*ih", hscale, vscale);
> + ret = insert_filter(&last_filter, &pad_idx, "scale", scale_buf);
> + }
> + }
> +
> +
> theta = get_rotation(displaymatrix);
>
> if (fabs(theta - 90) < 1.0) {
> diff --git a/fftools/ffmpeg_opt.c b/fftools/ffmpeg_opt.c
> index f6551621c3..4fae6cbfbf 100644
> --- a/fftools/ffmpeg_opt.c
> +++ b/fftools/ffmpeg_opt.c
> @@ -121,6 +121,8 @@ static const char *const opt_name_bits_per_raw_sample[] = {"bits_per_raw_s
> double rotation;
> int hflip;
> int vflip;
> + double hscale;
> + double vscale;
> };
> #define OFFSET(x) offsetof(struct display_matrix_s, x)
> static const AVOption display_matrix_args[] = {
> @@ -130,6 +132,10 @@ static const char *const opt_name_bits_per_raw_sample[] = {"bits_per_raw_s
> { .i64 = -1 }, 0, 1, AV_OPT_FLAG_ARGUMENT},
> { "vflip", "set vflip", OFFSET(vflip), AV_OPT_TYPE_BOOL,
> { .i64 = -1 }, 0, 1, AV_OPT_FLAG_ARGUMENT},
> + { "hscale", "set scale factor", OFFSET(hscale), AV_OPT_TYPE_DOUBLE,
> + { .dbl = 1.0f }, 0.0f, 2.0f, AV_OPT_FLAG_ARGUMENT},
> + { "vscale", "set scale factor", OFFSET(vscale), AV_OPT_TYPE_DOUBLE,
> + { .dbl = 1.0f }, 0.0f, 2.0f, AV_OPT_FLAG_ARGUMENT},
> { NULL },
> };
> static const AVClass class_display_matrix_args = {
> @@ -848,6 +854,8 @@ static void add_display_matrix_to_stream(OptionsContext *o,
> .rotation = DBL_MAX,
> .hflip = -1,
> .vflip = -1,
> + .hscale = 1.0f,
> + .vscale = 1.0f,
> };
>
> AVDictionary *global_args = NULL;
> @@ -903,6 +911,8 @@ static void add_display_matrix_to_stream(OptionsContext *o,
> av_display_matrix_flip((int32_t *)buf,
> hflip_set ? test_args.hflip : 0,
> vflip_set ? test_args.vflip : 0);
> +
> + av_display_matrix_scale((int32_t *)buf, test_args.hscale, test_args.vscale);
> }
>
>
> diff --git a/libavutil/display.c b/libavutil/display.c
> index d31061283c..b89763ff48 100644
> --- a/libavutil/display.c
> +++ b/libavutil/display.c
> @@ -28,9 +28,11 @@
>
> // fixed point to double
> #define CONV_FP(x) ((double) (x)) / (1 << 16)
> +#define CONV_FP2(x) ((double) (x)) / (1 << 30)
>
> // double to fixed point
> #define CONV_DB(x) (int32_t) ((x) * (1 << 16))
> +#define CONV_DB2(x) (int32_t) ((x) * (1 << 30))
>
> double av_display_rotation_get(const int32_t matrix[9])
> {
> @@ -48,6 +50,17 @@ double av_display_rotation_get(const int32_t matrix[9])
> return -rotation;
> }
>
> +double av_display_hscale_get(const int32_t matrix[9])
> +{
> + return fabs(CONV_FP2(matrix[2]));
> +}
> +
> +double av_display_vscale_get(const int32_t matrix[9])
> +{
> + return fabs(CONV_FP2(matrix[5]));
> +}
> +
> +#include <stdio.h>
> void av_display_rotation_set(int32_t matrix[9], double angle)
> {
> double radians = -angle * M_PI / 180.0f;
> @@ -60,6 +73,8 @@ void av_display_rotation_set(int32_t matrix[9], double angle)
> matrix[1] = CONV_DB(-s);
> matrix[3] = CONV_DB(s);
> matrix[4] = CONV_DB(c);
> + matrix[2] = 1 << 30;
> + matrix[5] = 1 << 30;
?
> matrix[8] = 1 << 30;
> }
>
> @@ -72,3 +87,9 @@ void av_display_matrix_flip(int32_t matrix[9], int hflip, int vflip)
> for (i = 0; i < 9; i++)
> matrix[i] *= flip[i % 3];
> }
> +
> +void av_display_matrix_scale(int32_t matrix[9], double hscale, double vscale)
> +{
> + matrix[2] = CONV_DB2(CONV_FP2(matrix[2]) * hscale);
> + matrix[5] = CONV_DB2(CONV_FP2(matrix[5]) * vscale);
matrix[2] and matrix[5] correspond to u and v in the matrix in
display.h. These values need to be zero or you don't have an affine, but
a projective transformation.
> +}
> diff --git a/libavutil/display.h b/libavutil/display.h
> index 31d8bef361..b875e1cfdd 100644
> --- a/libavutil/display.h
> +++ b/libavutil/display.h
> @@ -86,6 +86,26 @@
> */
> double av_display_rotation_get(const int32_t matrix[9]);
>
> +/**
> + * Extract the horizontal scaling component of the transformation matrix.
> + *
> + * @param matrix the transformation matrix
> + * @return the horizontal scaling by which the transformation matrix scales the frame
> + * in the horizontal direction. The scaling factor will be in the range
> + * [0.0, 2.0].
> + */
> +double av_display_hscale_get(const int32_t matrix[9]);
> +
> +/**
> + * Extract the vertical scaling component of the transformation matrix.
> + *
> + * @param matrix the transformation matrix
> + * @return the vertical scaling by which the transformation matrix scales the frame
> + * in the vertical direction. The scaling factor will be in the range
> + * [0.0, 2.0].
> + */
> +double av_display_vscale_get(const int32_t matrix[9]);
> +
> /**
> * Initialize a transformation matrix describing a pure clockwise
> * rotation by the specified angle (in degrees).
> @@ -105,6 +125,14 @@ void av_display_rotation_set(int32_t matrix[9], double angle);
> */
> void av_display_matrix_flip(int32_t matrix[9], int hflip, int vflip);
>
> +/**
> + * Scale the input matrix horizontally and/or vertically.
> + *
> + * @param matrix an allocated transformation matrix
> + * @param hscale whether the matrix should be scaled horizontally
> + * @param vscale whether the matrix should be scaled vertically
> + */
> +void av_display_matrix_scale(int32_t matrix[9], double hscale, double vscale);
> /**
> * @}
> * @}
1. Once again: Separate lavu patches from fftools patches.
2. What makes you believe that every matrix has something like a
horizontal scaling factor? What about rotations by 90°?
3. What makes you believe that 2 and 5 are the right elements? They are
not. These elements must be zero or you have a projective
transformation. If you made an off-by-one error and thought 1 and 4
(i.e. b and d in the notation of display.h), it is still wrong, as
scaling in one direction needs to scale two matrix elements.
4. Even if one restricts oneself to simple diagonal matrices (i.e. b = c
= u = v = 0), your formulae for av_display_[hv]scale_get are wrong,
because they use the wrong matrix elements and because you completely
ignore w, i.e. matrix[8]. And of course the scaling range can be much
greater than just [0, 2].
5. Finally, missing APIchanges and version entry stuff.
- Andreas
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