Re: [FFmpeg-devel] [PATCH] FFMPEG: add graph reconfig capability

["softworkz ." <softworkz-at-hotmail.com@ffmpeg.org>]

> -----Original Message-----
> From: ffmpeg-devel <ffmpeg-devel-bounces@ffmpeg.org> On Behalf Of
> yangyalei050 via ffmpeg-devel
> Sent: Dienstag, 25. März 2025 12:25
> To: ffmpeg-devel@ffmpeg.org
> Cc: 269032741@qq.com
> Subject: [FFmpeg-devel] [PATCH] FFMPEG: add graph reconfig capability
> 
> From: yangyalei <269032741@qq.com>
> 
> 1. Support reuse the graph to play different audio.
> 2. Support config part of the graph.
> 
> Signed-off-by: yangyalei <269032741@qq.com>
> ---
>  libavfilter/avfilter.c      |   8 +-
>  libavfilter/avfiltergraph.c | 201 ++++++++++++++++++++++++++++++++----
>  2 files changed, 187 insertions(+), 22 deletions(-)
> 
> diff --git a/libavfilter/avfilter.c b/libavfilter/avfilter.c
> index e732556ffa..71396674fe 100644
> --- a/libavfilter/avfilter.c
> +++ b/libavfilter/avfilter.c
> @@ -345,7 +345,8 @@ int ff_filter_config_links(AVFilterContext *filter)
>          FilterLinkInternal *li = ff_link_internal(link);
>          FilterLinkInternal *li_in;
> 
> -        if (!link) continue;
> +        if (!link || !link->incfg.formats || !link->outcfg.formats)
> +            continue;
>          if (!link->src || !link->dst) {
>              av_log(filter, AV_LOG_ERROR,
>                     "Not all input and output are properly linked
> (%d).\n", i);
> @@ -359,6 +360,11 @@ int ff_filter_config_links(AVFilterContext *filter)
> 
>          switch (li->init_state) {
>          case AVLINK_INIT:
> +            /* for part graph re-negotiation.
> +             * For example: output-filter link has config_props,
> +             * but the input-filter still need config_props. */
> +            if ((ret = ff_filter_config_links(link->src)) < 0)
> +                return ret;
>              continue;
>          case AVLINK_STARTINIT:
>              av_log(filter, AV_LOG_INFO, "circular filter chain
> detected\n");
> diff --git a/libavfilter/avfiltergraph.c b/libavfilter/avfiltergraph.c
> index 5e93f93aab..8565fe6a24 100644
> --- a/libavfilter/avfiltergraph.c
> +++ b/libavfilter/avfiltergraph.c
> @@ -23,6 +23,7 @@
>  #include "config.h"
> 
>  #include <string.h>
> +#include <stdbool.h>
> 
>  #include "libavutil/avassert.h"
>  #include "libavutil/bprint.h"
> @@ -348,7 +349,7 @@ static int filter_query_formats(AVFilterContext
> *ctx)
> 
>      if (filter->formats_state == FF_FILTER_FORMATS_QUERY_FUNC) {
>          if ((ret = filter->formats.query_func(ctx)) < 0) {
> -            if (ret != AVERROR(EAGAIN))
> +            if (ret != AVERROR(EAGAIN) && ret != FFERROR_NOT_READY)
>                  av_log(ctx, AV_LOG_ERROR, "Query format failed for
> '%s': %s\n",
>                         ctx->name, av_err2str(ret));
>              return ret;
> @@ -390,7 +391,7 @@ static int filter_query_formats(AVFilterContext
> *ctx)
>          av_freep(&cfg_in_dyn);
>          av_freep(&cfg_out_dyn);
>          if (ret < 0) {
> -            if (ret != AVERROR(EAGAIN))
> +            if (ret != AVERROR(EAGAIN) && ret != FFERROR_NOT_READY)
>                  av_log(ctx, AV_LOG_ERROR, "Query format failed for
> '%s': %s\n",
>                         ctx->name, av_err2str(ret));
>              return ret;
> @@ -438,6 +439,81 @@ static int formats_declared(AVFilterContext *f)
>      return 1;
>  }
> 
> +static void ff_avfilter_link_unref_formats(AVFilterLink *link)
> +{
> +    ff_formats_unref(&link->incfg.formats);
> +    ff_formats_unref(&link->outcfg.formats);
> +    ff_formats_unref(&link->incfg.samplerates);
> +    ff_formats_unref(&link->outcfg.samplerates);
> +    ff_channel_layouts_unref(&link->incfg.channel_layouts);
> +    ff_channel_layouts_unref(&link->outcfg.channel_layouts);

What about color_spaces and color_ranges?
Below you are removing the unref for those, but you don't add them here or elsewhere again.



> +}
> +
> +static bool formats_useless(AVFilterContext *f)
> +{
> +    bool in, out;
> +    int i;
> +
> +    if (!f->nb_inputs || !f->nb_outputs)
> +        return false;
> +
> +    in = out = true;
> +
> +    for (i = 0; i < f->nb_inputs; i++)
> +        if (f->inputs[i]->outcfg.formats) {
> +            in = false;
> +            break;
> +        }
> +
> +    for (i = 0; i < f->nb_outputs; i++)
> +        if (f->outputs[i]->incfg.formats) {
> +            out = false;
> +            break;
> +        }
> +
> +    return in ^ out;
> +}
> +
> +
> +static bool sanitize_formats(AVFilterGraph *graph)
> +{
> +    AVFilterContext *f;
> +    bool changed = false;
> +    unsigned i, j;
> +
> +    for (i = 0; i < graph->nb_filters; i++) {
> +        f = graph->filters[i];
> +
> +        for (j = 0; j < f->nb_inputs; j++) {
> +            if ((!f->inputs[j]->outcfg.formats && f->inputs[j]-
> >incfg.formats)
> +                 || (f->inputs[j]->outcfg.formats && !f->inputs[j]-
> >incfg.formats)) {
> +                ff_avfilter_link_unref_formats(f->inputs[j]);
> +                changed = true;
> +            }
> +        }
> +
> +        for (j = 0; j < f->nb_outputs; j++) {
> +            if ((!f->outputs[j]->incfg.formats && f->outputs[j]-
> >outcfg.formats)
> +                || (f->outputs[j]->incfg.formats && !f->outputs[j]-
> >outcfg.formats)) {
> +                ff_avfilter_link_unref_formats(f->outputs[j]);
> +                changed = true;
> +            }
> +        }
> +
> +        if (formats_useless(f)) {
> +            for (j = 0; j < f->nb_inputs; j++)
> +                ff_avfilter_link_unref_formats(f->inputs[j]);
> +
> +            for (j = 0; j < f->nb_outputs; j++)
> +                ff_avfilter_link_unref_formats(f->outputs[j]);
> +
> +            changed = true;
> +        }
> +    }
> +
> +    return changed;
> +}
> +
>  /**
>   * Perform one round of query_formats() and merging formats lists on
> the
>   * filter graph.
> @@ -462,7 +538,7 @@ static int query_formats(AVFilterGraph *graph, void
> *log_ctx)
>          if (formats_declared(f))
>              continue;
>          ret = filter_query_formats(f);
> -        if (ret < 0 && ret != AVERROR(EAGAIN))
> +        if (ret < 0 && ret != AVERROR(EAGAIN) && ret !=
> FFERROR_NOT_READY)
>              return ret;
>          /* note: EAGAIN could indicate a partial success, not counted
> yet */
>          count_queried += ret >= 0;
> @@ -478,7 +554,7 @@ static int query_formats(AVFilterGraph *graph, void
> *log_ctx)
>              unsigned neg_step;
>              int convert_needed = 0;
> 
> -            if (!link)
> +            if (!link || !link->incfg.formats)
>                  continue;
> 
>              neg = ff_filter_get_negotiation(link);
> @@ -492,6 +568,7 @@ static int query_formats(AVFilterGraph *graph, void
> *log_ctx)
>                      break;
>                  }
>              }
> +
>              for (neg_step = 0; neg_step < neg->nb_mergers; neg_step++)
> {
>                  const AVFilterFormatsMerger *m = &neg-
> >mergers[neg_step];
>                  void *a = FF_FIELD_AT(void *, m->offset, link->incfg);
> @@ -789,17 +866,6 @@ static int pick_format(AVFilterLink *link,
> AVFilterLink *ref)
>              return ret;
>      }
> 
> -    ff_formats_unref(&link->incfg.formats);
> -    ff_formats_unref(&link->outcfg.formats);
> -    ff_formats_unref(&link->incfg.samplerates);
> -    ff_formats_unref(&link->outcfg.samplerates);
> -    ff_channel_layouts_unref(&link->incfg.channel_layouts);
> -    ff_channel_layouts_unref(&link->outcfg.channel_layouts);
> -    ff_formats_unref(&link->incfg.color_spaces);
> -    ff_formats_unref(&link->outcfg.color_spaces);
> -    ff_formats_unref(&link->incfg.color_ranges);
> -    ff_formats_unref(&link->outcfg.color_ranges);

The latter 4 are removed without replacement.


>      return 0;
>  }
> 
> @@ -818,6 +884,7 @@ do {
> \
>              list_type *fmts;
> \
> 
> \
>              if (link->type != out_link->type ||
> \
> +                !out_link->incfg.list ||
> \
>                  out_link->incfg.list->nb == 1)
> \
>                  continue;
> \
>              fmts = out_link->incfg.list;
> \
> @@ -925,6 +992,7 @@ static void
> swap_samplerates_on_filter(AVFilterContext *filter)
>          link = filter->inputs[i];
> 
>          if (link->type == AVMEDIA_TYPE_AUDIO &&
> +            link->outcfg.samplerates &&
>              link->outcfg.samplerates->nb_formats== 1)
>              break;
>      }
> @@ -938,6 +1006,7 @@ static void
> swap_samplerates_on_filter(AVFilterContext *filter)
>          int best_idx, best_diff = INT_MAX;
> 
>          if (outlink->type != AVMEDIA_TYPE_AUDIO ||
> +            !outlink->incfg.samplerates ||
>              outlink->incfg.samplerates->nb_formats < 2)
>              continue;
> 
> @@ -1007,6 +1076,7 @@ static void
> swap_channel_layouts_on_filter(AVFilterContext *filter)
>          link = filter->inputs[i];
> 
>          if (link->type == AVMEDIA_TYPE_AUDIO &&
> +            link->outcfg.channel_layouts &&
>              link->outcfg.channel_layouts->nb_channel_layouts == 1)
>              break;
>      }
> @@ -1018,6 +1088,7 @@ static void
> swap_channel_layouts_on_filter(AVFilterContext *filter)
>          int best_idx = -1, best_score = INT_MIN, best_count_diff =
> INT_MAX;
> 
>          if (outlink->type != AVMEDIA_TYPE_AUDIO ||
> +            !outlink->incfg.channel_layouts ||
>              outlink->incfg.channel_layouts->nb_channel_layouts < 2)
>              continue;
> 
> @@ -1110,6 +1181,7 @@ static void
> swap_sample_fmts_on_filter(AVFilterContext *filter)
>          link = filter->inputs[i];
> 
>          if (link->type == AVMEDIA_TYPE_AUDIO &&
> +            link->outcfg.formats &&
>              link->outcfg.formats->nb_formats == 1)
>              break;
>      }
> @@ -1124,6 +1196,7 @@ static void
> swap_sample_fmts_on_filter(AVFilterContext *filter)
>          int best_idx = -1, best_score = INT_MIN;
> 
>          if (outlink->type != AVMEDIA_TYPE_AUDIO ||
> +            !outlink->incfg.formats ||
>              outlink->incfg.formats->nb_formats < 2)
>              continue;
> 
> @@ -1180,7 +1253,8 @@ static int pick_formats(AVFilterGraph *graph)
>              AVFilterContext *filter = graph->filters[i];
>              if (filter->nb_inputs){
>                  for (j = 0; j < filter->nb_inputs; j++){
> -                    if (filter->inputs[j]->incfg.formats && filter-
> >inputs[j]->incfg.formats->nb_formats == 1) {
> +                    if (filter->inputs[j]->format < 0 &&
> +                        filter->inputs[j]->incfg.formats && filter-
> >inputs[j]->incfg.formats->nb_formats == 1) {
>                          if ((ret = pick_format(filter->inputs[j],
> NULL)) < 0)
>                              return ret;
>                          change = 1;
> @@ -1189,7 +1263,8 @@ static int pick_formats(AVFilterGraph *graph)
>              }
>              if (filter->nb_outputs){
>                  for (j = 0; j < filter->nb_outputs; j++){
> -                    if (filter->outputs[j]->incfg.formats && filter-
> >outputs[j]->incfg.formats->nb_formats == 1) {
> +                    if (filter->outputs[j]->format < 0 &&
> +                        filter->outputs[j]->incfg.formats && filter-
> >outputs[j]->incfg.formats->nb_formats == 1) {
>                          if ((ret = pick_format(filter->outputs[j],
> NULL)) < 0)
>                              return ret;
>                          change = 1;
> @@ -1198,7 +1273,7 @@ static int pick_formats(AVFilterGraph *graph)
>              }
>              if (filter->nb_inputs && filter->nb_outputs && filter-
> >inputs[0]->format>=0) {
>                  for (j = 0; j < filter->nb_outputs; j++) {
> -                    if (filter->outputs[j]->format<0) {
> +                    if (filter->outputs[j]->format < 0 && filter-
> >outputs[j]->incfg.formats) {
>                          if ((ret = pick_format(filter->outputs[j],
> filter->inputs[0])) < 0)
>                              return ret;
>                          change = 1;
> @@ -1234,6 +1309,8 @@ static int graph_config_formats(AVFilterGraph
> *graph, void *log_ctx)
>      if (ret < 0)
>          return ret;
> 
> +    while (sanitize_formats(graph));
> +
>      /* Once everything is merged, it's possible that we'll still have
>       * multiple valid media format choices. We try to minimize the
> amount
>       * of format conversion inside filters */
> @@ -1292,12 +1369,94 @@ static int graph_config_pointers(AVFilterGraph
> *graph, void *log_ctx)
>      return 0;
>  }
> 
> +static void graph_clear_formats(AVFilterGraph *graph, void *log_ctx)
> +{
> +    int status_in, status_out;
> +    AVRational time_base;
> +    AVFilterContext *f;
> +    FilterLinkInternal *ilinki;
> +    FilterLinkInternal *olinki;
> +    int i, j;
> +
> +    for (i = graph->nb_filters - 1; i >= 0; i--) {
> +        f = graph->filters[i];
> +
> +        if (!strncmp(f->name, "auto_", strlen("auto_"))) {
> +            ilinki = ff_link_internal(f->inputs[0]);
> +            olinki = ff_link_internal(f->outputs[0]);
> +            if (ilinki->status_out || ilinki->status_in ||
> +                olinki->status_out || olinki->status_in) {
> +                AVFilterContext *src = f->inputs[0]->src;
> +                AVFilterContext *dst = f->outputs[0]->dst;
> +                unsigned srcpad = FF_OUTLINK_IDX(f->inputs[0]);
> +                unsigned dstpad = FF_INLINK_IDX(f->outputs[0]);
> +
> +                status_in  = ilinki->status_in;
> +                status_out = ilinki->status_out;
> +                time_base  = f->inputs[0]->time_base;
> +
> +                avfilter_free(f);
> +                avfilter_link(src, srcpad, dst, dstpad);
> +
> +                olinki->status_in  = status_in;
> +                olinki->status_out = status_out;
> +                dst->inputs[0]->time_base  = time_base;
> +
> +                ff_filter_set_ready(dst, 200);
> +                continue;
> +            }
> +        }
> +
> +        for (j = 0; j < f->nb_inputs; j++) {
> +            ilinki = ff_link_internal(f->inputs[j]);
> +            if (ilinki->status_out) {
> +                ff_formats_unref(&f->inputs[j]->outcfg.formats);
> +                ff_formats_unref(&f->inputs[j]->outcfg.samplerates);
> +                ff_channel_layouts_unref(&f->inputs[j]-
> >outcfg.channel_layouts);
> +
> +                if (ilinki->status_in) {
> +                    f->inputs[j]->format         = -1;
> +                    f->inputs[j]->sample_rate    = 0;
> +                    ilinki->init_state     = AVLINK_UNINIT;
> +                    f->inputs[j]->time_base.num  = 0;
> +                    f->inputs[j]->time_base.den  = 0;
> +                    av_channel_layout_uninit(&f->inputs[j]->ch_layout);
> +                }
> +            }
> +        }
> +
> +        for (j = 0; j < f->nb_outputs; j++) {
> +            olinki = ff_link_internal(f->outputs[j]);
> +            if (olinki->status_in) {
> +                ff_formats_unref(&f->outputs[j]->incfg.formats);
> +                ff_formats_unref(&f->outputs[j]->incfg.samplerates);
> +                ff_channel_layouts_unref(&f->outputs[j]-
> >incfg.channel_layouts);
> +
> +                if (olinki->status_out) {
> +                    f->outputs[j]->format         = -1;
> +                    f->outputs[j]->sample_rate    = 0;
> +                    olinki->init_state     = AVLINK_UNINIT;
> +                    f->outputs[j]->time_base.num  = 0;
> +                    f->outputs[j]->time_base.den  = 0;
> +                    av_channel_layout_uninit(&f->outputs[j]-
> >ch_layout);
> +                }

The code above is executed for audio and video filters but it seems to be handling audio filters only.


> +            }
> +        }
> +    }
> +}
> +
>  int avfilter_graph_config(AVFilterGraph *graphctx, void *log_ctx)
>  {
> -    int ret;
> +    AVClass *avc = log_ctx ? *(AVClass **)log_ctx : NULL;
> +    int ret, i;
> 
> -    if ((ret = graph_check_validity(graphctx, log_ctx)))
> -        return ret;

This is the only usage of graph_check_validity(), so you would need to remove that function as well, explaining why it is no longer needed.


> -----Original Message-----
> From: ffmpeg-devel <ffmpeg-devel-bounces@ffmpeg.org> On Behalf Of
> yangyalei via ffmpeg-devel
> Sent: Mittwoch, 26. März 2025 04:10
> To: FFmpeg development discussions and patches <ffmpeg-devel@ffmpeg.org>
> Cc: yangyalei <269032741@qq.com>
> Subject: Re: [FFmpeg-devel] [PATCH] FFMPEG: add graph reconfig
> capability
> (abuff_src@Music)(abuff_src@Ring)---amix---abuff_sink
> 
> 
> In the graph above, We support three playback scenarios at the same
> time:
> 
> 
> 1. Only abuff_src@Music needs to be played, and abuff_src@Ring has no
> data. abuff_src@Ring is ignored during negotiation, "abuff_src@Music --
> amix -- abuff_sink" link negotiation is successful, and playback can be
> performed;
> 
> 
> 2. Only abuff_src@Ring needs to be played, and abuff_src@Music has no
> data. abuff_src@Music is ignored during negotiation, "abuff_src@ring --
> &gt; amix --&gt; abuff_sink" link negotiation is successful, and
> playback can be performed;
> 
> 
> 3. Both abuff_src@Music and abuff_src@Ring need to be played, and all
> filters are negotiated successfully and mixed playback is performed.


Is this case about the ffmpeg CLI tool or are you using libavfilter directly?

In the latter case: Why don't you just remove the source filter which has no data, what's the purpose of keeping a filter without data flow in the graph?

Your patch enables a filter to remain in the graph without having any formats negotiated but is still connected to other filters. What's not quite clear to me: How can this work in your example with the amix filter?
If the amix filter has two connected inputs but one of those inputs does not deliver any data, I would expect that the graph processing gets stuck at the amix filter input where it is waiting for data from the second input, isn't that the case?

Thanks
sw





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