[FFmpeg-devel] [PATCH] Add new vf_tiltandshift filter

[Andreas Rheinhardt]

Vittorio Giovara:
> +#include "avfilter.h"
> +#include "formats.h"
> +#include "internal.h"
> +#include "video.h"
> +
> +#define TILT_NONE  -1
> +#define TILT_FRAME  0
> +#define TILT_BLACK  1

Why is this not an enum?

> +
> +typedef struct FrameList {
> +    AVFrame *frame;
> +    struct FrameList *next;
> +} FrameList;
> +
> +typedef struct TiltandshiftContext {
> +    const AVClass *class;
> +
> +    /* set when all input frames have been processed and we have to
> +     * empty buffers, pad and then return */
> +    int eof_recv;
> +
> +    /* live or static sliding */
> +    int tilt;
> +
> +    /* initial or final actions to perform (pad/hold a 
> frame/black/nothing) */
> +    int start;
> +    int end;
> +
> +    /* columns to hold or pad at the beginning or at the end 
> (respectively) */
> +    int hold;
> +    int pad;
> +
> +    /* buffers for black columns */
> +    uint8_t *black_buffers[4];
> +    int black_linesizes[4];
> +
> +    /* list containing all input frames */
> +    size_t input_size;
> +    FrameList *input;
> +    FrameList *prev;
> +
> +    const AVPixFmtDescriptor *desc;
> +} TiltandshiftContext;
> +
> +static int list_add_frame(FrameList **list, size_t *size, AVFrame 
> *frame)
> +{
> +    FrameList *element = av_mallocz(sizeof(FrameList));

The overhead of this FrameList is unnecessary: You can simply use
AVFrame.opaque as your next pointer.

> +    if (!element)
> +        return AVERROR(ENOMEM);
> +
> +    element->frame = frame;
> +
> +    if (*list == NULL) {
> +        *list = element;
> +    } else {
> +        FrameList *head = *list;
> +        while (head->next)
> +            head = head->next;
> +        head->next = element;
> +    }
> +
> +    (*size)++;
> +    return 0;
> +}
> +
> +static void list_remove_head(FrameList **list, size_t *size)
> +{
> +    FrameList *head = *list;
> +    if (head) {
> +        av_frame_free(&head->frame);
> +        *list = head->next;
> +        av_freep(&head);
> +    }
> +
> +    (*size)--;
> +}
> +
> +static const enum AVPixelFormat formats_supported[] = {
> +    AV_PIX_FMT_YUV420P, AV_PIX_FMT_YUV422P, AV_PIX_FMT_YUV444P,
> +    AV_PIX_FMT_YUV410P,
> +    AV_PIX_FMT_YUVJ420P, AV_PIX_FMT_YUVJ422P, AV_PIX_FMT_YUVJ444P,
> +    AV_PIX_FMT_YUVJ440P,
> +    AV_PIX_FMT_NONE
> +};
> +
> +static int query_formats(AVFilterContext *ctx)
> +{
> +    return ff_set_common_formats(ctx, 
> ff_make_format_list(formats_supported));

Unnecessary. Use FILTER_PIXFMTS_ARRAY.


> +
> +AVFilter ff_vf_tiltandshift = {

const AVFilter

> +    .name          = "tiltandshift",
> +    .description   = NULL_IF_CONFIG_SMALL("Generate a tilt-and-shift'd 
> video."),
> +    .priv_size     = sizeof(TiltandshiftContext),
> +    .priv_class    = &tiltandshift_class,
> +    .uninit        = uninit,
> +    FILTER_INPUTS(tiltandshift_inputs),
> +    FILTER_OUTPUTS(tiltandshift_outputs),
> +    FILTER_QUERY_FUNC(query_formats),
> +};