core: add infrastructure to get screenshots from VOs

Add a VO command (VOCTRL_SCREENSHOT) which requests a screenshot
directly from the VO. If VO support is available, screenshots will be
taken instantly (no more 1 or 2 frames delay). Taking screenshots when
hardware decoding is in use will also work (vdpau). Additionally, the
screenshots will now use the same colorspace as the video display.
Change the central MPContext to be allocated with talloc so that it
can be used as a talloc parent context.

This commit does not yet implement the functionality for any VO (added
in subsequent commits).

The old screenshot video filter is not needed anymore if VO support is
present, and in that case will not be used even if it is present in
the filter chain. If VO support is not available then the filter is
used like before. Note that the filter still has some of the old
problems, such as delaying the screenshot by at least 1 frame.

1 files changed, 230 insertions, 0 deletions

diff --git a/screenshot.c b/screenshot.c
new file mode 100644
index 0000000000..e05bbfe480
--- /dev/null
+++ b/screenshot.c
@@ -0,0 +1,230 @@
+/*
+ * This file is part of mplayer2.
+ *
+ * mplayer2 is free software; you can redistribute it and/or modify
+ * it under the terms of the GNU General Public License as published by
+ * the Free Software Foundation; either version 2 of the License, or
+ * (at your option) any later version.
+ *
+ * mplayer2 is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License along
+ * with mplayer2; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA.
+ */
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <inttypes.h>
+
+#include <sys/types.h>
+#include <sys/stat.h>
+#include <unistd.h>
+
+#include <libswscale/swscale.h>
+#include <libavcodec/avcodec.h>
+
+#include "config.h"
+#include "talloc.h"
+#include "screenshot.h"
+#include "mp_core.h"
+#include "mp_msg.h"
+#include "libmpcodecs/img_format.h"
+#include "libmpcodecs/mp_image.h"
+#include "libmpcodecs/dec_video.h"
+#include "libmpcodecs/vf.h"
+#include "libvo/video_out.h"
+
+#include "fmt-conversion.h"
+
+//for sws_getContextFromCmdLine and mp_sws_set_colorspace
+#include "libmpcodecs/vf_scale.h"
+#include "libvo/csputils.h"
+
+typedef struct screenshot_ctx {
+    int each_frame;
+    int using_vf_screenshot;
+
+    int frameno;
+    char fname[102];
+} screenshot_ctx;
+
+static screenshot_ctx *screenshot_get_ctx(MPContext *mpctx)
+{
+    if (!mpctx->screenshot_ctx)
+        mpctx->screenshot_ctx = talloc_zero(mpctx, screenshot_ctx);
+    return mpctx->screenshot_ctx;
+}
+
+static int write_png(screenshot_ctx *ctx, struct mp_image *image)
+{
+    char *fname = ctx->fname;
+    FILE *fp = NULL;
+    void *outbuffer = NULL;
+    int success = 0;
+
+    AVCodecContext *avctx = avcodec_alloc_context();
+    if (!avctx)
+        goto error_exit;
+
+    if (avcodec_open(avctx, avcodec_find_encoder(CODEC_ID_PNG))) {
+        mp_msg(MSGT_CPLAYER, MSGL_INFO, "Could not open libavcodec PNG encoder"
+               " for saving screenshot\n");
+        goto error_exit;
+    }
+
+    avctx->width = image->width;
+    avctx->height = image->height;
+    avctx->pix_fmt = PIX_FMT_RGB24;
+    avctx->compression_level = 0;
+
+    size_t outbuffer_size = image->width * image->height * 3 * 2;
+    outbuffer = malloc(outbuffer_size);
+    if (!outbuffer)
+        goto error_exit;
+
+    AVFrame pic;
+    pic.data[0] = image->planes[0];
+    pic.linesize[0] = image->stride[0];
+    int size = avcodec_encode_video(avctx, outbuffer, outbuffer_size, &pic);
+    if (size < 1)
+        goto error_exit;
+
+    fp = fopen(fname, "wb");
+    if (fp == NULL) {
+        avcodec_close(avctx);
+        mp_msg(MSGT_CPLAYER, MSGL_ERR, "\nPNG Error opening %s for writing!\n",
+               fname);
+        goto error_exit;
+    }
+
+    fwrite(outbuffer, size, 1, fp);
+    fflush(fp);
+
+    if (ferror(fp))
+        goto error_exit;
+
+    success = 1;
+error_exit:
+    if (avctx)
+        avcodec_close(avctx);
+    if (fp)
+        fclose(fp);
+    free(outbuffer);
+    return success;
+}
+
+static int fexists(char *fname)
+{
+    struct stat dummy;
+    if (stat(fname, &dummy) == 0)
+        return 1;
+    else
+        return 0;
+}
+
+static void gen_fname(screenshot_ctx *ctx)
+{
+    do {
+        snprintf(ctx->fname, 100, "shot%04d.png", ++ctx->frameno);
+    } while (fexists(ctx->fname) && ctx->frameno < 100000);
+    if (fexists(ctx->fname)) {
+        ctx->fname[0] = '\0';
+        return;
+    }
+
+    mp_msg(MSGT_CPLAYER, MSGL_INFO, "*** screenshot '%s' ***\n", ctx->fname);
+
+}
+
+void screenshot_save(struct MPContext *mpctx, struct mp_image *image)
+{
+    screenshot_ctx *ctx = screenshot_get_ctx(mpctx);
+    struct mp_image *dst = alloc_mpi(image->w, image->h, IMGFMT_RGB24);
+
+    struct SwsContext *sws = sws_getContextFromCmdLine(image->width,
+                                                       image->height,
+                                                       image->imgfmt,
+                                                       dst->width,
+                                                       dst->height,
+                                                       dst->imgfmt);
+
+    struct mp_csp_details colorspace;
+    get_detected_video_colorspace(mpctx->sh_video, &colorspace);
+    // this is a property of the output device; images always use full-range RGB
+    colorspace.levels_out = MP_CSP_LEVELS_PC;
+    mp_sws_set_colorspace(sws, &colorspace);
+
+    sws_scale(sws, (const uint8_t **)image->planes, image->stride, 0,
+              image->height, dst->planes, dst->stride);
+
+    gen_fname(ctx);
+    write_png(ctx, dst);
+
+    sws_freeContext(sws);
+    free_mp_image(dst);
+}
+
+static void vf_screenshot_callback(void *pctx, struct mp_image *image)
+{
+    struct MPContext *mpctx = (struct MPContext *)pctx;
+    screenshot_ctx *ctx = screenshot_get_ctx(mpctx);
+    screenshot_save(mpctx, image);
+    if (ctx->each_frame)
+        screenshot_request(mpctx, 0);
+}
+
+void screenshot_request(struct MPContext *mpctx, bool each_frame)
+{
+    if (mpctx->video_out && mpctx->video_out->config_ok) {
+        screenshot_ctx *ctx = screenshot_get_ctx(mpctx);
+
+        ctx->using_vf_screenshot = 0;
+
+        if (each_frame) {
+            ctx->each_frame = !ctx->each_frame;
+            if (!ctx->each_frame)
+                return;
+        }
+
+        struct voctrl_screenshot_args args;
+        if (vo_control(mpctx->video_out, VOCTRL_SCREENSHOT, &args) == true) {
+            screenshot_save(mpctx, args.out_image);
+            free_mp_image(args.out_image);
+        } else {
+            mp_msg(MSGT_CPLAYER, MSGL_INFO, "No VO support for taking"
+                   " screenshots, trying VFCTRL_SCREENSHOT!\n");
+            ctx->using_vf_screenshot = 1;
+            struct vf_ctrl_screenshot cmd = {
+                .image_callback = vf_screenshot_callback,
+                .image_callback_ctx = mpctx,
+            };
+            struct vf_instance *vfilter = mpctx->sh_video->vfilter;
+            if (vfilter->control(vfilter, VFCTRL_SCREENSHOT, &cmd) !=
+                    CONTROL_OK)
+                mp_msg(MSGT_CPLAYER, MSGL_INFO,
+                       "...failed (need --vf=screenshot?)\n");
+        }
+    }
+}
+
+void screenshot_flip(struct MPContext *mpctx)
+{
+    screenshot_ctx *ctx = screenshot_get_ctx(mpctx);
+
+    if (!ctx->each_frame)
+        return;
+
+    // screenshot_flip is called when the VO presents a new frame. vf_screenshot
+    // can behave completely different (consider filters inserted between
+    // vf_screenshot and vf_vo, that add or remove frames), so handle this case
+    // somewhere else.
+    if (ctx->using_vf_screenshot)
+        return;
+
+    screenshot_request(mpctx, 0);
+}