Re: [FFmpeg-devel] [PATCH 2/2] libavfilter/vf_fps: Rewrite using activate callback
Just a few comments on your review:
On Sun, 2018-02-18 at 19:01 +0100, Nicolas George wrote:
> > @@ -91,31 +94,46 @@ static av_cold int init(AVFilterContext *ctx)
> > {
> > FPSContext *s = ctx->priv;
> >
> > -if (!(s->fifo = av_fifo_alloc_array(2, sizeof(AVFrame*
> > -return AVERROR(ENOMEM);
> > +/* Pass INT64_MIN/MAX through unchanged to avoid special cases
> > for AV_NOPTS_VALUE */
> > +s->rounding = s->rounding | AV_ROUND_PASS_MINMAX;
>
> Since rounding is exposed as an option with explicit bounds, it would
> probably be better to keep AV_ROUND_PASS_MINMAX out of the field and
> only include it when actually calling av_rescale_q_rnd().
Makes sense, easy change.
> > @@ -128,194 +146,238 @@ static int config_props(AVFilterLink* link)
> >
> > link->time_base = av_inv_q(s->framerate);
> > link->frame_rate= s->framerate;
> > -link->w = link->src->inputs[0]->w;
> > -link->h = link->src->inputs[0]->h;
>
> Looks unrelated.
I can split this into a separate cleanup patch, then.
> > +
> > +/* Convert the start time option to output timebase and save
> > it */
> > +if (s->start_time != DBL_MAX && s->start_time !=
> > AV_NOPTS_VALUE) {
> > +double first_pts = s->start_time * AV_TIME_BASE;
> > +first_pts = FFMIN(FFMAX(first_pts, INT64_MIN), INT64_MAX);
>
> It would probably better to issue an error when the value is out of
> representable range.
I'll make this a fatal error. I considered adjusting the range of
accepted values on the AVOption, but it would be tricky to get right,
with rounding issues and whatnot (and I'm not sure that using DBL_MAX
as an invalid/default value would still work).
>
> > +s->start_pts = av_rescale_q_rnd(first_pts, AV_TIME_BASE_Q,
> > +link->time_base, s->rounding);
>
> Nit: indentation.
Do you prefer the style of matching the indentation level of wrapped
parameters to the ( of the function? I can do that, I'll try to make it
consistent in the file.
> > -return ret;
> > -}
> > +ret = ff_inlink_consume_frame(inlink, &frame);
> > +/* Caller must have run ff_inlink_check_available_frame first
> > */
> > +av_assert1(ret);
>
> Negative error codes must still be checked.
Ah, took me a moment looking at this function's return values again to
understand why this was needed. I'll add the error handling code.
> > +
> > +ret = ff_filter_frame(outlink, frame);
> > +if (ret >= 0) {
> > +s->frames_out++;
> > +s->dup += dup;
> > +}
>
> Minor nit: I would rather have "if (ret < 0) return ret;" and make
> the
> incrementation unconditional.
Making the incrementation unconditional simplifies the flow quite a
bit, I'll make that change.
> > [static int void write_frame_eof()]
> This whole function seems to implement the very same logic as
> write_frame() with just s->status_pts instead of s->frames[1]->pts. It
> should be factored.
I thought about doing this, but it'll make the conditionals quite a bit
more complicated. I'll spend some time trying to figure out a better
way to handle this.
> > +static void update_eof_pts(AVFilterContext *ctx, FPSContext *s,
> > AVFilterLink *inlink, AVFilterLink *outlink)
> > +{
> > +/* Convert status_pts to outlink timebase */
> > +int eof_rounding = (s->eof_action == EOF_ACTION_PASS) ? AV_ROUND_UP :
> > s->rounding;
> > +s->status_pts = av_rescale_q_rnd(s->status_pts, inlink->time_base,
> > +outlink->time_base, eof_rounding);
>
> Nit: indentation. Also, I do not like the fact that s->status_pts can be
> in different time bases depending on the part of the code. I would
> prefer if ff_inlink_acknowledge_status() is used with a temp variable,
> passed as argument to update_eof_pts(), and only the s->status_pts is
> set.
This is something that was bugging me a bit as well, I'll make the
change.
> >
> > -s->frames_out++;
> > +/* Buffered frames are available, so generate an output frame */
> > +if (s->frames_count == 2 && ff_outlink_frame_wanted(outlink) >= 0)
> > {
>
> Do not check ff_outlink_frame_wanted() here: if the filter is activated
> and can produce a frame, produce it.
Alright.
>
> > +ret = write_frame(ctx, s, outlink);
> > +/* Couldn't generate a frame: e.g. a frame was dropped */
> > +if (ret == AVERROR(EAGAIN)) {
> > +/* Schedule us to perform another step */
> > +ff_filter_set_ready(ctx, 100);
> > +return 0;
> > +}
>
> I do not like the use of EAGAIN for this. It may conflict with strange
> error codes returned by other filters. It should not happen, but it
> could. I would advice to define a specific error code for this file
> only, like FFERROR_REDO in libavformat/internal.h. Or, even better, add
> "int *again" as an extra argument to write_frame() and return the
> condition like that.
I like the solution w
Re: [FFmpeg-devel] [PATCH 2/2] libavfilter/vf_fps: Rewrite using activate callback
Hi Nicolas, On Sun, 2018-02-18 at 19:01 +0100, Nicolas George wrote: > > Thanks for the patch. It was something I had in my TODO list for a > long > time. The code looks very good. Here are a few comments below. Of > course > open to discussion. Thanks for the review. I'm going to spend some time going over it now. I've noticed in my testing that I completely forgot to hook up the 'start_time' option, so expect a patch respin fixing that and addressing your comments as well. (I'll look at writing some tests for the start_time option too.) -- Calvin Walton ___ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
Re: [FFmpeg-devel] [PATCH 2/2] libavfilter/vf_fps: Rewrite using activate callback
On 16.02.2018 21:09, calvin.wal...@kepstin.ca wrote: Oops, I forgot to remove this bit from the changelog: On Fri, 2018-02-16 at 15:02 -0500, Calvin Walton wrote: TODO: This is still a work in progress. It may have different behaviour in some cases from the old fps filter. I have not yet implemented the "eof_action" option, since I haven't figured out what it's supposed to do. At this point I'm fairly confident that the behaviour matches the existing filter, and that I've gotten the eof_action behaviour correct as well. I have run this patch against some private test files with filter options "fps=1:round=near:eof_action=pass" and found no regressions. So eof_action seems to work fine, indeed. Regards, Tobias ___ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
Re: [FFmpeg-devel] [PATCH 2/2] libavfilter/vf_fps: Rewrite using activate callback
Calvin Walton (2018-02-16):
> The old version of the filter had a problem where it would queue up
> all of the duplicate frames required to fill a timestamp gap in a
> single call to filter_frame. In problematic files - I've hit this in
> webcam streams with large gaps due to network issues - this will queue
> up a potentially huge number of frames. (I've seen it trigger the Linux
> OOM-killer on particularly large pts gaps.)
>
> This revised version of the filter using the activate callback will
> generate at most 1 frame each time it is called, and respects output
> links having the frame_wanted_out set to a negative number to indicate
> that they don't want frames.
Thanks for the patch. It was something I had in my TODO list for a long
time. The code looks very good. Here are a few comments below. Of course
open to discussion.
>
> TODO: This is still a work in progress. It may have different behaviour
> in some cases from the old fps filter. I have not yet implemented the
> "eof_action" option, since I haven't figured out what it's supposed to
> do.
> ---
> libavfilter/vf_fps.c | 398
> +--
> 1 file changed, 230 insertions(+), 168 deletions(-)
>
> diff --git a/libavfilter/vf_fps.c b/libavfilter/vf_fps.c
> index dbafd2c35a..16e432db0b 100644
> --- a/libavfilter/vf_fps.c
> +++ b/libavfilter/vf_fps.c
> @@ -2,6 +2,7 @@
> * Copyright 2007 Bobby Bingham
> * Copyright 2012 Robert Nagy
> * Copyright 2012 Anton Khirnov
> + * Copyright 2018 Calvin Walton
> *
> * This file is part of FFmpeg.
> *
> @@ -28,17 +29,12 @@
> #include
> #include
>
> -#include "libavutil/common.h"
> -#include "libavutil/fifo.h"
> +#include "libavutil/avassert.h"
> #include "libavutil/mathematics.h"
> #include "libavutil/opt.h"
> -#include "libavutil/parseutils.h"
> -
> -#define FF_INTERNAL_FIELDS 1
> -#include "framequeue.h"
> #include "avfilter.h"
> +#include "filters.h"
> #include "internal.h"
> -#include "video.h"
>
> enum EOFAction {
> EOF_ACTION_ROUND,
> @@ -49,17 +45,24 @@ enum EOFAction {
> typedef struct FPSContext {
> const AVClass *class;
>
> -AVFifoBuffer *fifo; ///< store frames until we get two successive
> timestamps
> -
> -/* timestamps in input timebase */
> -int64_t first_pts; ///< pts of the first frame that arrived on this
> filter
> -
> +/* Options */
> double start_time; ///< pts, in seconds, of the expected first frame
> -
> AVRational framerate; ///< target framerate
> int rounding; ///< AVRounding method for timestamps
> int eof_action; ///< action performed for last frame in FIFO
>
> +/* Set during outlink configuration */
> +int64_t start_pts; ///< pts of the expected first frame
> +
> +/* Runtime state */
> +int status;///< buffered input status
> +int64_t status_pts;///< buffered input status timestamp
> +
> +AVFrame *frames[2]; ///< buffered frames
> +int frames_count; ///< number of buffered frames
> +
> +int64_t next_pts; ///< pts of the next frame to output
> +
> /* statistics */
> int frames_in; ///< number of frames on input
> int frames_out;///< number of frames on output
> @@ -91,31 +94,46 @@ static av_cold int init(AVFilterContext *ctx)
> {
> FPSContext *s = ctx->priv;
>
> -if (!(s->fifo = av_fifo_alloc_array(2, sizeof(AVFrame*
> -return AVERROR(ENOMEM);
> +/* Pass INT64_MIN/MAX through unchanged to avoid special cases for
> AV_NOPTS_VALUE */
> +s->rounding = s->rounding | AV_ROUND_PASS_MINMAX;
Since rounding is exposed as an option with explicit bounds, it would
probably be better to keep AV_ROUND_PASS_MINMAX out of the field and
only include it when actually calling av_rescale_q_rnd().
>
> -s->first_pts= AV_NOPTS_VALUE;
> +s->start_pts= AV_NOPTS_VALUE;
> +s->status_pts = AV_NOPTS_VALUE;
> +s->next_pts = AV_NOPTS_VALUE;
>
> av_log(ctx, AV_LOG_VERBOSE, "fps=%d/%d\n", s->framerate.num,
> s->framerate.den);
> return 0;
> }
>
> -static void flush_fifo(AVFifoBuffer *fifo)
> +/* Remove the first frame from the buffer, returning it */
> +static AVFrame *shift_frame(FPSContext *s)
> {
> -while (av_fifo_size(fifo)) {
> -AVFrame *tmp;
> -av_fifo_generic_read(fifo, &tmp, sizeof(tmp), NULL);
> -av_frame_free(&tmp);
> -}
> +AVFrame *frame;
> +
> +/* Must only be called when there are frames in the buffer */
> +av_assert1(s->frames_count > 0);
> +
> +frame = s->frames[0];
> +s->frames[0] = s->frames[1];
> +s->frames[1] = NULL;
> +s->frames_count--;
> +
> +return frame;
> }
>
> static av_cold void uninit(AVFilterContext *ctx)
> {
> FPSContext *s = ctx->priv;
> -if (s->fifo) {
> -s->drop += av_fifo_size(s->fifo) / sizeof(AVFrame*);
> -flush_fifo(s->fifo);
> -
Re: [FFmpeg-devel] [PATCH 2/2] libavfilter/vf_fps: Rewrite using activate callback
Oops, I forgot to remove this bit from the changelog: On Fri, 2018-02-16 at 15:02 -0500, Calvin Walton wrote: > TODO: This is still a work in progress. It may have different > behaviour > in some cases from the old fps filter. I have not yet implemented the > "eof_action" option, since I haven't figured out what it's supposed > to > do. At this point I'm fairly confident that the behaviour matches the existing filter, and that I've gotten the eof_action behaviour correct as well. Cheers! Calvin. ___ ffmpeg-devel mailing list ffmpeg-devel@ffmpeg.org http://ffmpeg.org/mailman/listinfo/ffmpeg-devel
