On date Wednesday 2014-07-30 23:44:46 +0200, Nicolas George encoded:
> Metaframes are frames without data, identified by a negative
> format code, used to carry special conditions.
> They are sent only to filter that declare supporting them.
> The only metaframe for now is EOF; this mechanism augments
> the current mechanism based on request_frame() returning
> AVERROR_EOF, with the advantage that the EOF metaframe carries
> a timestamp.
> The metaframes are a purely internal API and do not leak to
> the application.
>
> Signed-off-by: Nicolas George <geo...@nsup.org>
> ---
> libavfilter/avfilter.c | 73
> +++++++++++++++++++++++++++++++++++++++++++++-----
> libavfilter/internal.h | 34 +++++++++++++++++++++++
> 2 files changed, 100 insertions(+), 7 deletions(-)
>
>
> Changed the name to "metaframes".
> Allocate the frame with the classic method.
>
>
> diff --git a/libavfilter/avfilter.c b/libavfilter/avfilter.c
> index 7b11467..7894173 100644
> --- a/libavfilter/avfilter.c
> +++ b/libavfilter/avfilter.c
> @@ -346,15 +346,16 @@ int ff_request_frame(AVFilterLink *link)
> ret = link->srcpad->request_frame(link);
> else if (link->src->inputs[0])
> ret = ff_request_frame(link->src->inputs[0]);
> - if (ret == AVERROR_EOF && link->partial_buf) {
> - AVFrame *pbuf = link->partial_buf;
> - link->partial_buf = NULL;
> - ret = ff_filter_frame_framed(link, pbuf);
> - }
> if (ret < 0) {
> + if (!link->frame_requested) {
> + av_assert0(ret == AVERROR_EOF);
> + ret = 0;
> + }
> link->frame_requested = 0;
> - if (ret == AVERROR_EOF)
> - link->closed = 1;
> + if (ret == AVERROR_EOF) {
> + ret = ff_filter_link_close(link, AV_NOPTS_VALUE);
> + return ret < 0 ? ret : AVERROR_EOF;
> + }
> } else {
> av_assert0(!link->frame_requested ||
> link->flags & FF_LINK_FLAG_REQUEST_LOOP);
> @@ -1132,10 +1133,52 @@ static int ff_filter_frame_needs_framing(AVFilterLink
> *link, AVFrame *frame)
> return ret;
> }
>
> +static int ff_filter_metaframe(AVFilterLink *link, AVFrame *frame)
> +{
> + AVFrame *pbuf = link->partial_buf;
> + int ret;
> +
> + if (pbuf) {
> + link->partial_buf = NULL;
> + if ((ret = ff_filter_frame_framed(link, pbuf)) < 0)
> + return ret;
> + }
> +
> + if ((link->dst->filter->flags & FF_FILTER_FLAG_SUPPORT_METAFRAMES)) {
> + ret = link->dstpad->filter_frame ?
> + link->dstpad->filter_frame(link, frame) :
> + default_filter_frame(link, frame);
> + if (ret < 0)
> + return ret;
It shall probably execute the remaining part of the function even in
case of failure.
> + }
> +
> + switch (frame->format) {
> +
> + case FF_METAFRAME_EOF:
> + link->closed = 1;
> + break;
> +
> + case 0:
> + case FF_METAFRAME_NOP:
> + /* Not implemented yet because not used either for now.
> + Caveat: if the same metaframe is forwarded to the next filter
> + and the next filter changes the type, the type change must not be
> + taken into account for the first link. */
I find this a bit confusing. Can you explain why the NOP metaframe is
needed?
> +
> + default:
> + av_assert0(!"reached");
> + }
> +
> + return ret;
> +}
> +
> int ff_filter_frame(AVFilterLink *link, AVFrame *frame)
> {
> FF_TPRINTF_START(NULL, filter_frame); ff_tlog_link(NULL, link, 1);
> ff_tlog(NULL, " "); ff_tlog_ref(NULL, frame, 1);
>
> + if (frame->format < -1)
> + return ff_filter_metaframe(link, frame);
> +
> /* Consistency checks */
> if (link->type == AVMEDIA_TYPE_VIDEO) {
> if (strcmp(link->dst->filter->name, "scale")) {
> @@ -1162,6 +1205,22 @@ int ff_filter_frame(AVFilterLink *link, AVFrame *frame)
> }
> }
>
> +int ff_filter_link_close(AVFilterLink *link, int64_t pts)
> +{
> + AVFrame *frame;
> + int ret;
> +
> + if (link->closed)
> + return 0;
> + if (!(frame = av_frame_alloc()))
> + return AVERROR(ENOMEM);
> + frame->format = FF_METAFRAME_EOF;
> + frame->pts = pts;
> + ret = ff_filter_frame(link, frame);
> + av_frame_free(&frame);
> + return ret;
> +}
> +
> const AVClass *avfilter_get_class(void)
> {
> return &avfilter_class;
> diff --git a/libavfilter/internal.h b/libavfilter/internal.h
> index 308b115..fbe603a 100644
> --- a/libavfilter/internal.h
> +++ b/libavfilter/internal.h
> @@ -374,4 +374,38 @@ AVFilterContext *ff_filter_alloc(const AVFilter *filter,
> const char *inst_name);
> */
> void ff_filter_graph_remove_filter(AVFilterGraph *graph, AVFilterContext
> *filter);
>
> +/**
> + * The filter can accept metaframes.
> + * Metaframes are AVFrame structures with a negative format field.
> + * The framework will take default actions based on the metaframe type.
> + * The destination filter is allowed to reset the type to inhibit the
> + * default actions.
> + */
> +#define FF_FILTER_FLAG_SUPPORT_METAFRAMES (1 << 24)
> +
> +/**
> + * Types of metaframes that can be passer to a filter.
> + */
> +enum {
> + /**
> + * Do not do anything.
> + * Can be used by the destination filter to inhibit default handling.
> + */
> + FF_METAFRAME_NOP = -1,
> +
> + /**
> + * The input has reached EOF.
> + * The pts field holds the timestamp of the end of the stream,
> + * therefore allowing to compute the duration of the last frame.
> + * The frame structure still belongs to the framework and must not be
> + * stored by the destination filter; it also may be incomplete.
> + */
> + FF_METAFRAME_EOF = AVERROR_EOF,
> +};
> +
> +/**
> + * Close the link by sending the EOF metaframes to the destination filter.
> + */
> +int ff_filter_link_close(AVFilterLink *link, int64_t pts);
> +
> #endif /* AVFILTER_INTERNAL_H */
LGTM otherwise.
--
FFmpeg = Foolish Forgiving Mortal Power Exxagerate Gnome
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