[FFmpeg-cvslog] vf_hwmap: Add reverse mapping for hardware frames
Mark Thompson
git at videolan.org
Mon Oct 30 23:03:20 EET 2017
ffmpeg | branch: master | Mark Thompson <sw at jkqxz.net> | Sat Mar 4 23:57:42 2017 +0000| [81a4cb8e58636d4efd200c2b4fec786a7e948d8b] | committer: Mark Thompson
vf_hwmap: Add reverse mapping for hardware frames
This is something of a hack. It allocates a new hwframe context for
the target format, then maps it back to the source link and overwrites
the input link hw_frames_ctx so that the previous filter will receive
the frames we want from ff_get_video_buffer(). It may fail if
the previous filter imposes any additional constraints on the frames
it wants to use as output.
> http://git.videolan.org/gitweb.cgi/ffmpeg.git/?a=commit;h=81a4cb8e58636d4efd200c2b4fec786a7e948d8b
---
libavfilter/vf_hwmap.c | 68 ++++++++++++++++++++++++++++++++++++++++++++------
1 file changed, 61 insertions(+), 7 deletions(-)
diff --git a/libavfilter/vf_hwmap.c b/libavfilter/vf_hwmap.c
index f19d10f2c2..2983528ea0 100644
--- a/libavfilter/vf_hwmap.c
+++ b/libavfilter/vf_hwmap.c
@@ -34,7 +34,7 @@ typedef struct HWMapContext {
int mode;
char *derive_device_type;
- int map_backwards;
+ int reverse;
} HWMapContext;
static int hwmap_query_formats(AVFilterContext *avctx)
@@ -92,7 +92,8 @@ static int hwmap_config_output(AVFilterLink *outlink)
}
if (inlink->format == hwfc->format &&
- (desc->flags & AV_PIX_FMT_FLAG_HWACCEL)) {
+ (desc->flags & AV_PIX_FMT_FLAG_HWACCEL) &&
+ !ctx->reverse) {
// Map between two hardware formats (including the case of
// undoing an existing mapping).
@@ -113,6 +114,56 @@ static int hwmap_config_output(AVFilterLink *outlink)
goto fail;
}
+ } else if (inlink->format == hwfc->format &&
+ (desc->flags & AV_PIX_FMT_FLAG_HWACCEL) &&
+ ctx->reverse) {
+ // Map between two hardware formats, but do it in reverse.
+ // Make a new hwframe context for the target type, and then
+ // overwrite the input hwframe context with a derived context
+ // mapped from that back to the source type.
+ AVBufferRef *source;
+ AVHWFramesContext *frames;
+
+ ctx->hwframes_ref = av_hwframe_ctx_alloc(device);
+ if (!ctx->hwframes_ref) {
+ err = AVERROR(ENOMEM);
+ goto fail;
+ }
+ frames = (AVHWFramesContext*)ctx->hwframes_ref->data;
+
+ frames->format = outlink->format;
+ frames->sw_format = hwfc->sw_format;
+ frames->width = hwfc->width;
+ frames->height = hwfc->height;
+ frames->initial_pool_size = 64;
+
+ err = av_hwframe_ctx_init(ctx->hwframes_ref);
+ if (err < 0) {
+ av_log(avctx, AV_LOG_ERROR, "Failed to initialise "
+ "target frames context: %d.\n", err);
+ goto fail;
+ }
+
+ err = av_hwframe_ctx_create_derived(&source,
+ inlink->format,
+ hwfc->device_ref,
+ ctx->hwframes_ref,
+ ctx->mode);
+ if (err < 0) {
+ av_log(avctx, AV_LOG_ERROR, "Failed to create "
+ "derived source frames context: %d.\n", err);
+ goto fail;
+ }
+
+ // Here is the naughty bit. This overwriting changes what
+ // ff_get_video_buffer() in the previous filter returns -
+ // it will now give a frame allocated here mapped back to
+ // the format it expects. If there were any additional
+ // constraints on the output frames there then this may
+ // break nastily.
+ av_buffer_unref(&inlink->hw_frames_ctx);
+ inlink->hw_frames_ctx = source;
+
} else if ((outlink->format == hwfc->format &&
inlink->format == hwfc->sw_format) ||
inlink->format == hwfc->format) {
@@ -144,13 +195,13 @@ static int hwmap_config_output(AVFilterLink *outlink)
if (!device) {
av_log(avctx, AV_LOG_ERROR, "A device reference is "
- "required to create new frames with backwards "
+ "required to create new frames with reverse "
"mapping.\n");
err = AVERROR(EINVAL);
goto fail;
}
- ctx->map_backwards = 1;
+ ctx->reverse = 1;
ctx->hwframes_ref = av_hwframe_ctx_alloc(device);
if (!ctx->hwframes_ref) {
@@ -167,7 +218,7 @@ static int hwmap_config_output(AVFilterLink *outlink)
err = av_hwframe_ctx_init(ctx->hwframes_ref);
if (err < 0) {
av_log(avctx, AV_LOG_ERROR, "Failed to create frame "
- "context for backward mapping: %d.\n", err);
+ "context for reverse mapping: %d.\n", err);
goto fail;
}
@@ -199,7 +250,7 @@ static AVFrame *hwmap_get_buffer(AVFilterLink *inlink, int w, int h)
AVFilterLink *outlink = avctx->outputs[0];
HWMapContext *ctx = avctx->priv;
- if (ctx->map_backwards) {
+ if (ctx->reverse && !inlink->hw_frames_ctx) {
AVFrame *src, *dst;
int err;
@@ -257,7 +308,7 @@ static int hwmap_filter_frame(AVFilterLink *link, AVFrame *input)
goto fail;
}
- if (ctx->map_backwards && !input->hw_frames_ctx) {
+ if (ctx->reverse && !input->hw_frames_ctx) {
// If we mapped backwards from hardware to software, we need
// to attach the hardware frame context to the input frame to
// make the mapping visible to av_hwframe_map().
@@ -323,6 +374,9 @@ static const AVOption hwmap_options[] = {
{ "derive_device", "Derive a new device of this type",
OFFSET(derive_device_type), AV_OPT_TYPE_STRING,
{ .str = NULL }, 0, 0, FLAGS },
+ { "reverse", "Map in reverse (create and allocate in the sink)",
+ OFFSET(reverse), AV_OPT_TYPE_INT,
+ { .i64 = 0 }, 0, 1, FLAGS },
{ NULL },
};
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