This is useful to simulate random jitter. --- Changelog | 1 + doc/filters.texi | 10 +++++++++- libavfilter/setpts.c | 39 +++++++++++++++++++++++++++++++++------ 3 files changed, 43 insertions(+), 7 deletions(-)
diff --git a/Changelog b/Changelog index 424bfc11af..ed01c53264 100644 --- a/Changelog +++ b/Changelog @@ -15,6 +15,7 @@ version <next>: - tiltandshift filter - qrencode filter and qrencodesrc source - quirc filter +- lavfi/setpts: introduce rand() function in expression version 6.1: - libaribcaption decoder diff --git a/doc/filters.texi b/doc/filters.texi index d1f95b9781..1d9a5d6c7d 100644 --- a/doc/filters.texi +++ b/doc/filters.texi @@ -30946,7 +30946,7 @@ The expression which is evaluated for each frame to construct its timestamp. @end table The expression is evaluated through the eval API and can contain the following -constants: +constants and functions: @table @option @item FRAME_RATE, FR @@ -31010,6 +31010,8 @@ The timebase of the input timestamps. @item T_CHANGE Time of the first frame after command was applied or time of the first frame if no commands. +@item rand(min, max) +a random number included between min and max @end table @subsection Examples @@ -31021,6 +31023,12 @@ Start counting PTS from zero setpts=PTS-STARTPTS @end example +@item +Apply a random jitter effect of +/-100 TB units: +@example +setpts=PTS+100rand(-100\,100) +@end example + @item Apply fast motion effect: @example diff --git a/libavfilter/setpts.c b/libavfilter/setpts.c index 88a8d6af86..0f24a900b3 100644 --- a/libavfilter/setpts.c +++ b/libavfilter/setpts.c @@ -32,6 +32,8 @@ #include "libavutil/internal.h" #include "libavutil/mathematics.h" #include "libavutil/opt.h" +#include "libavutil/lfg.h" +#include "libavutil/random_seed.h" #include "libavutil/time.h" #include "audio.h" #include "avfilter.h" @@ -101,18 +103,39 @@ typedef struct SetPTSContext { AVExpr *expr; double var_values[VAR_VARS_NB]; enum AVMediaType type; + AVLFG lfg; } SetPTSContext; #define V(name_) \ setpts->var_values[VAR_##name_] +static double drand(void *ctx, double min, double max) +{ + SetPTSContext *setpts = ((AVFilterContext *)ctx)->priv; + + return min + (max-min) / UINT_MAX * av_lfg_get(&setpts->lfg); +} + +typedef double (*eval_func2)(void *, double a, double b); + +static const eval_func2 fun2[] = { + drand, + NULL +}; + +static const char *const fun2_names[] = { + "rand" +}; + static av_cold int init(AVFilterContext *ctx) { SetPTSContext *setpts = ctx->priv; int ret; + av_lfg_init(&setpts->lfg, av_get_random_seed()); + if ((ret = av_expr_parse(&setpts->expr, setpts->expr_str, - var_names, NULL, NULL, NULL, NULL, 0, ctx)) < 0) { + var_names, NULL, NULL, fun2_names, fun2, 0, ctx)) < 0) { av_log(ctx, AV_LOG_ERROR, "Error while parsing expression '%s'\n", setpts->expr_str); return ret; } @@ -126,6 +149,7 @@ static av_cold int init(AVFilterContext *ctx) V(STARTPTS) = NAN; V(STARTT) = NAN; V(T_CHANGE) = NAN; + return 0; } @@ -159,8 +183,10 @@ static inline char *double2int64str(char *buf, double v) return buf; } -static double eval_pts(SetPTSContext *setpts, AVFilterLink *inlink, AVFrame *frame, int64_t pts) +static double eval_pts(AVFilterContext *ctx, AVFilterLink *inlink, AVFrame *frame, int64_t pts) { + SetPTSContext *setpts = ctx->priv; + if (isnan(V(STARTPTS))) { V(STARTPTS) = TS2D(pts); V(STARTT ) = TS2T(pts, inlink->time_base); @@ -186,17 +212,18 @@ FF_ENABLE_DEPRECATION_WARNINGS } } - return av_expr_eval(setpts->expr, setpts->var_values, NULL); + return av_expr_eval(setpts->expr, setpts->var_values, ctx); } #define d2istr(v) double2int64str((char[BUF_SIZE]){0}, v) static int filter_frame(AVFilterLink *inlink, AVFrame *frame) { - SetPTSContext *setpts = inlink->dst->priv; + AVFilterContext *ctx = inlink->dst; + SetPTSContext *setpts = ctx->priv; int64_t in_pts = frame->pts; double d; - d = eval_pts(setpts, inlink, frame, frame->pts); + d = eval_pts(ctx, inlink, frame, frame->pts); frame->pts = D2TS(d); av_log(inlink->dst, AV_LOG_TRACE, @@ -250,7 +277,7 @@ static int activate(AVFilterContext *ctx) return filter_frame(inlink, in); if (ff_inlink_acknowledge_status(inlink, &status, &pts)) { - double d = eval_pts(setpts, inlink, NULL, pts); + double d = eval_pts(ctx, inlink, NULL, pts); av_log(ctx, AV_LOG_TRACE, "N:EOF PTS:%s T:%f -> PTS:%s T:%f\n", d2istr(V(PTS)), V(T), d2istr(d), TS2T(d, inlink->time_base)); -- 2.34.1 _______________________________________________ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org https://ffmpeg.org/mailman/listinfo/ffmpeg-devel To unsubscribe, visit link above, or email ffmpeg-devel-requ...@ffmpeg.org with subject "unsubscribe".