lavfi: pass the hw frames context through the filter chain

doc/APIchanges

@@ -13,6 +13,10 @@ libavutil:     2015-08-28
 
 API changes, most recent first:
 
+2016-xx-xx - lavfi 6.2.0 - avfilter.h
+  xxxxxxx avfilter.h - Add AVFilterLink.hw_frames_ctx.
+  xxxxxxx buffersrc.h - Add AVBufferSrcParameters and functions for handling it.
+
 2016-xx-xx - lavu 55.6.0
   xxxxxxx buffer.h - Add av_buffer_pool_init2().
   xxxxxxx hwcontext.h - Add a new installed header hwcontext.h with a new API

doc/filters.texi

@@ -2864,6 +2864,10 @@ The time base used for input timestamps.
 @item sar
 The sample (pixel) aspect ratio of the input video.
 
+@item hw_frames_ctx
+When using a hardware pixel format, this should be a reference to an
+AVHWFramesContext describing input frames.
+
 @end table
 
 For example:

libavfilter/avfilter.c

@@ -20,8 +20,10 @@
  */
 
 #include "libavutil/avstring.h"
+#include "libavutil/buffer.h"
 #include "libavutil/channel_layout.h"
 #include "libavutil/common.h"
+#include "libavutil/hwcontext.h"
 #include "libavutil/imgutils.h"
 #include "libavutil/internal.h"
 #include "libavutil/opt.h"
@@ -217,6 +219,17 @@ int avfilter_config_links(AVFilterContext *filter)
                     return ret;
                 }
 
+            if (link->src->nb_inputs && link->src->inputs[0]->hw_frames_ctx &&
+                !link->hw_frames_ctx) {
+                AVHWFramesContext *input_ctx = (AVHWFramesContext*)link->src->inputs[0]->hw_frames_ctx->data;
+
+                if (input_ctx->format == link->format) {
+                    link->hw_frames_ctx = av_buffer_ref(link->src->inputs[0]->hw_frames_ctx);
+                    if (!link->hw_frames_ctx)
+                        return AVERROR(ENOMEM);
+                }
+            }
+
             link->init_state = AVLINK_INIT;
         }
     }
@@ -481,6 +494,8 @@ static void free_link(AVFilterLink *link)
     if (link->dst)
         link->dst->inputs[link->dstpad - link->dst->input_pads] = NULL;
 
+    av_buffer_unref(&link->hw_frames_ctx);
+
     ff_formats_unref(&link->in_formats);
     ff_formats_unref(&link->out_formats);
     ff_formats_unref(&link->in_samplerates);

libavfilter/avfilter.h

@@ -35,6 +35,7 @@
 
 #include "libavutil/attributes.h"
 #include "libavutil/avutil.h"
+#include "libavutil/buffer.h"
 #include "libavutil/frame.h"
 #include "libavutil/log.h"
 #include "libavutil/samplefmt.h"
@@ -387,6 +388,12 @@ struct AVFilterLink {
      * Sinks can use it to set a default output frame rate.
      */
     AVRational frame_rate;
+
+    /**
+     * For hwaccel pixel formats, this should be a reference to the
+     * AVHWFramesContext describing the frames.
+     */
+    AVBufferRef *hw_frames_ctx;
 };
 
 /**

libavfilter/buffersrc.c

@@ -52,6 +52,8 @@ typedef struct BufferSourceContext {
     char               *pix_fmt_str;
     AVRational        pixel_aspect;
 
+    AVBufferRef *hw_frames_ctx;
+
     /* audio only */
     int sample_rate;
     enum AVSampleFormat sample_fmt;
@@ -59,6 +61,7 @@ typedef struct BufferSourceContext {
     uint64_t channel_layout;
     char    *channel_layout_str;
 
+    int got_format_from_params;
     int eof;
 } BufferSourceContext;
 
@@ -75,6 +78,62 @@ typedef struct BufferSourceContext {
         return AVERROR(EINVAL);\
     }
 
+AVBufferSrcParameters *av_buffersrc_parameters_alloc(void)
+{
+    AVBufferSrcParameters *par = av_mallocz(sizeof(*par));
+    if (!par)
+        return NULL;
+
+    par->format = -1;
+
+    return par;
+}
+
+int av_buffersrc_parameters_set(AVFilterContext *ctx, AVBufferSrcParameters *param)
+{
+    BufferSourceContext *s = ctx->priv;
+
+    if (param->time_base.num > 0 && param->time_base.den > 0)
+        s->time_base = param->time_base;
+
+    switch (ctx->filter->outputs[0].type) {
+    case AVMEDIA_TYPE_VIDEO:
+        if (param->format != AV_PIX_FMT_NONE) {
+            s->got_format_from_params = 1;
+            s->pix_fmt = param->format;
+        }
+        if (param->width > 0)
+            s->w = param->width;
+        if (param->height > 0)
+            s->h = param->height;
+        if (param->sample_aspect_ratio.num > 0 && param->sample_aspect_ratio.den > 0)
+            s->pixel_aspect = param->sample_aspect_ratio;
+        if (param->frame_rate.num > 0 && param->frame_rate.den > 0)
+            s->frame_rate = param->frame_rate;
+        if (param->hw_frames_ctx) {
+            av_buffer_unref(&s->hw_frames_ctx);
+            s->hw_frames_ctx = av_buffer_ref(param->hw_frames_ctx);
+            if (!s->hw_frames_ctx)
+                return AVERROR(ENOMEM);
+        }
+        break;
+    case AVMEDIA_TYPE_AUDIO:
+        if (param->format != AV_SAMPLE_FMT_NONE) {
+            s->got_format_from_params = 1;
+            s->sample_fmt = param->format;
+        }
+        if (param->sample_rate > 0)
+            s->sample_rate = param->sample_rate;
+        if (param->channel_layout)
+            s->channel_layout = param->channel_layout;
+        break;
+    default:
+        return AVERROR_BUG;
+    }
+
+    return 0;
+}
+
 int attribute_align_arg av_buffersrc_write_frame(AVFilterContext *ctx, const AVFrame *frame)
 {
     AVFrame *copy;
@@ -150,11 +209,13 @@ static av_cold int init_video(AVFilterContext *ctx)
 {
     BufferSourceContext *c = ctx->priv;
 
-    if (!c->pix_fmt_str || !c->w || !c->h || av_q2d(c->time_base) <= 0) {
+    if (!(c->pix_fmt_str || c->got_format_from_params)  || !c->w || !c->h ||
+        av_q2d(c->time_base) <= 0) {
         av_log(ctx, AV_LOG_ERROR, "Invalid parameters provided.\n");
         return AVERROR(EINVAL);
     }
 
+    if (c->pix_fmt_str) {
         if ((c->pix_fmt = av_get_pix_fmt(c->pix_fmt_str)) == AV_PIX_FMT_NONE) {
             char *tail;
             c->pix_fmt = strtol(c->pix_fmt_str, &tail, 10);
@@ -163,6 +224,7 @@ static av_cold int init_video(AVFilterContext *ctx)
                 return AVERROR(EINVAL);
             }
         }
+    }
 
     if (!(c->fifo = av_fifo_alloc(sizeof(AVFrame*))))
         return AVERROR(ENOMEM);
@@ -223,14 +285,22 @@ static av_cold int init_audio(AVFilterContext *ctx)
     BufferSourceContext *s = ctx->priv;
     int ret = 0;
 
+    if (!(s->sample_fmt_str || s->got_format_from_params)) {
+        av_log(ctx, AV_LOG_ERROR, "Sample format not provided\n");
+        return AVERROR(EINVAL);
+    }
+    if (s->sample_fmt_str)
         s->sample_fmt = av_get_sample_fmt(s->sample_fmt_str);
+
     if (s->sample_fmt == AV_SAMPLE_FMT_NONE) {
         av_log(ctx, AV_LOG_ERROR, "Invalid sample format %s.\n",
                s->sample_fmt_str);
         return AVERROR(EINVAL);
     }
 
+    if (s->channel_layout_str)
         s->channel_layout = av_get_channel_layout(s->channel_layout_str);
+
     if (!s->channel_layout) {
         av_log(ctx, AV_LOG_ERROR, "Invalid channel layout %s.\n",
                s->channel_layout_str);
@@ -258,6 +328,7 @@ static av_cold void uninit(AVFilterContext *ctx)
         av_fifo_generic_read(s->fifo, &frame, sizeof(frame), NULL);
         av_frame_free(&frame);
     }
+    av_buffer_unref(&s->hw_frames_ctx);
     av_fifo_free(s->fifo);
     s->fifo = NULL;
 }
@@ -300,6 +371,12 @@ static int config_props(AVFilterLink *link)
         link->w = c->w;
         link->h = c->h;
         link->sample_aspect_ratio = c->pixel_aspect;
+
+        if (c->hw_frames_ctx) {
+            link->hw_frames_ctx = av_buffer_ref(c->hw_frames_ctx);
+            if (!link->hw_frames_ctx)
+                return AVERROR(ENOMEM);
+        }
         break;
     case AVMEDIA_TYPE_AUDIO:
         link->channel_layout = c->channel_layout;

libavfilter/buffersrc.h

@@ -34,6 +34,80 @@
  * @{
  */
 
+/**
+ * This structure contains the parameters describing the frames that will be
+ * passed to this filter.
+ *
+ * It should be allocated with av_buffersrc_parameters_alloc() and freed with
+ * av_free(). All the allocated fields in it remain owned by the caller.
+ */
+typedef struct AVBufferSrcParameters {
+    /**
+     * video: the pixel format, value corresponds to enum AVPixelFormat
+     * audio: the sample format, value corresponds to enum AVSampleFormat
+     */
+    int format;
+    /**
+     * The timebase to be used for the timestamps on the input frames.
+     */
+    AVRational time_base;
+
+    /**
+     * Video only, the display dimensions of the input frames.
+     */
+    int width, height;
+
+    /**
+     * Video only, the sample (pixel) aspect ratio.
+     */
+    AVRational sample_aspect_ratio;
+
+    /**
+     * Video only, the frame rate of the input video. This field must only be
+     * set to a non-zero value if input stream has a known constant framerate
+     * and should be left at its initial value if the framerate is variable or
+     * unknown.
+     */
+    AVRational frame_rate;
+
+    /**
+     * Video with a hwaccel pixel format only. This should be a reference to an
+     * AVHWFramesContext instance describing the input frames.
+     */
+    AVBufferRef *hw_frames_ctx;
+
+    /**
+     * Audio only, the audio sampling rate in samples per secon.
+     */
+    int sample_rate;
+
+    /**
+     * Audio only, the audio channel layout
+     */
+    uint64_t channel_layout;
+} AVBufferSrcParameters;
+
+/**
+ * Allocate a new AVBufferSrcParameters instance. It should be freed by the
+ * caller with av_free().
+ */
+AVBufferSrcParameters *av_buffersrc_parameters_alloc(void);
+
+/**
+ * Initialize the buffersrc or abuffersrc filter with the provided parameters.
+ * This function may be called multiple times, the later calls override the
+ * previous ones. Some of the parameters may also be set through AVOptions, then
+ * whatever method is used last takes precedence.
+ *
+ * @param ctx an instance of the buffersrc or abuffersrc filter
+ * @param param the stream parameters. The frames later passed to this filter
+ *              must conform to those parameters. All the allocated fields in
+ *              param remain owned by the caller, libavfilter will make internal
+ *              copies or references when necessary.
+ * @return 0 on success, a negative AVERROR code on failure.
+ */
+int av_buffersrc_parameters_set(AVFilterContext *ctx, AVBufferSrcParameters *param);
+
 /**
  * Add a frame to the buffer source.
  *

libavfilter/version.h

@@ -30,7 +30,7 @@
 #include "libavutil/version.h"
 
 #define LIBAVFILTER_VERSION_MAJOR  6
-#define LIBAVFILTER_VERSION_MINOR  1
+#define LIBAVFILTER_VERSION_MINOR  2
 #define LIBAVFILTER_VERSION_MICRO  0
 
 #define LIBAVFILTER_VERSION_INT AV_VERSION_INT(LIBAVFILTER_VERSION_MAJOR, \