Add vu-split

Signed-off-by: Mattias Andrée <maandree@kth.se>

3 files changed, 93 insertions, 1 deletions

diff --git a/Makefile b/Makefile
index 487fd85..182756a 100644
--- a/Makefile
+++ b/Makefile
@@ -19,6 +19,7 @@ BIN =\
 	vu-set-luma\
 	vu-set-saturation\
 	vu-single-colour\
+	vu-split\
 	vu-stack\
 	vu-to-image\
 	vu-write-head
diff --git a/TODO b/TODO
index 7d164ca..522878c 100644
--- a/TODO
+++ b/TODO
@@ -1,5 +1,4 @@
 vu-transpose		transpose frames
-vu-split		split a video into multiple vidoes
 vu-blur			gaussian blur, -c to only blur chroma
 vu-transform		transformation by matrix multiplication, -t for tiling, -s for improve quality
 				on downscaling (pixels' neighbours must not change)
diff --git a/src/vu-split.c b/src/vu-split.c
new file mode 100644
index 0000000..4d2bc02
--- /dev/null
+++ b/src/vu-split.c
@@ -0,0 +1,92 @@
+/* See LICENSE file for copyright and license details. */
+#include "arg.h"
+#include "stream.h"
+#include "util.h"
+
+#include <alloca.h>
+#include <fcntl.h>
+#include <inttypes.h>
+#include <limits.h>
+#include <string.h>
+#include <unistd.h>
+
+static void
+usage(void)
+{
+	eprintf("usage: %s (file end-point) ...\n", argv0);
+}
+
+int
+main(int argc, char *argv[])
+{
+	struct stream stream;
+	size_t *ends, i, parts, ptr, end, frame_size, max, ptw, n;
+	FILE *fp;
+	int fd;
+	ssize_t r;
+
+	ARGBEGIN {
+	default:
+		usage();
+	} ARGEND;
+
+	if (argc < 2 || argc % 2)
+		usage();
+
+	stream.file = "<stdin>";
+	stream.fd = STDIN_FILENO;
+	einit_stream(&stream);
+	if (stream.width > SIZE_MAX / stream.height)
+		eprintf("%s: video is too large\n", stream.file);
+	frame_size = stream.width * stream.height;
+	if (stream.frames > SSIZE_MAX / frame_size)
+		eprintf("%s: video is too large\n", stream.file);
+
+	parts = (size_t)argc / 2;
+	ends = alloca(parts * sizeof(*ends));
+
+	for (i = 0; i < parts; i++) {
+		if (!strcmp(argv[i * 2 + 1], "end"))
+			ends[i] = stream.frames;
+		else if (tozu(argv[i * 2 + 1], 0, SIZE_MAX, ends + i))
+			eprintf("the end point must be an integer in [0, %zu]\n", SIZE_MAX);
+		if (i && ends[i] <= ends[i - 1])
+			eprintf("the end points must be in strictly ascending order\n");
+		if (ends[i] > stream.frames)
+			eprintf("frame %zu is beyond the end of the video\n", ends[i]);
+	}
+
+	ptr = 0;
+	for (i = 0; i < parts; i++) {
+		fd = open(argv[i * 2], O_WRONLY);
+		if (fd < 0)
+			eprintf("open %s:", argv[i * 2]);
+		fp = fdopen(fd, "wb");
+
+		stream.frames = ends[i] - (i ? ends[i - 1] : 0);
+		fprint_stream_head(fp, &stream);
+		fflush(fp);
+		if (ferror(fp))
+			eprintf("%s:", argv[i * 2]);
+
+		for (end = ends[i] * frame_size; ptr < end; ptr += n) {
+			for (ptw = ptr; stream.ptr && ptw < end;) {
+				max = end - ptw;
+				max = max < stream.ptr ? max : stream.ptr;
+				r = write(fd, stream.buf, max);
+				if (r < 0)
+					eprintf("write %s:\n", argv[i * 2]);
+				memmove(stream.buf, stream.buf + r, stream.ptr - (size_t)r);
+			}
+			n = eread_stream(&stream, end - ptr);
+			if (n == 0)
+				eprintf("%s: file is shorter than expected\n", stream.file);
+		}
+
+		if (fclose(fp))
+			eprintf("%s:", argv[i * 2]);
+		close(fd);
+	}
+
+	return 0;
+}