[FFmpeg-devel] [PATCH] lavf: add subfile protocol.
Nicolas George
george at nsup.org
Tue Feb 25 21:55:13 CET 2014
Signed-off-by: Nicolas George <george at nsup.org>
---
Changelog | 1 +
doc/protocols.texi | 19 +++++++
libavformat/Makefile | 1 +
libavformat/allformats.c | 1 +
libavformat/subfile.c | 145 +++++++++++++++++++++++++++++++++++++++++++++++
libavformat/version.h | 2 +-
6 files changed, 168 insertions(+), 1 deletion(-)
create mode 100644 libavformat/subfile.c
diff --git a/Changelog b/Changelog
index 2785b3a..e57fc46 100644
--- a/Changelog
+++ b/Changelog
@@ -28,6 +28,7 @@ version <next>
- Support DNx444
- libx265 encoder
- dejudder filter
+- subfile protocol
version 2.1:
diff --git a/doc/protocols.texi b/doc/protocols.texi
index 2c84265..77772ae 100644
--- a/doc/protocols.texi
+++ b/doc/protocols.texi
@@ -949,6 +949,25 @@ this binary block are used as master key, the following 14 bytes are
used as master salt.
@end table
+ at section subfile
+
+Virtually extract a segment of a file or another stream.
+The underlying stream must be seekable.
+
+Accepted options:
+ at table @option
+ at item start
+Start offset of the extracted segment, in bytes.
+ at item end
+End offset of the extracted segment, in bytes.
+ at end table
+
+Example: extract a chapter from a DVD VOB file (start and end sectors
+obtained externally and multiplied by 2048):
+ at example
+subfile,,start,153391104,end,268142592,,:/media/dvd/VIDEO_TS/VTS_08_1.VOB
+ at end example
+
@section tcp
Trasmission Control Protocol.
diff --git a/libavformat/Makefile b/libavformat/Makefile
index 9ef81cc..dd13fd0 100644
--- a/libavformat/Makefile
+++ b/libavformat/Makefile
@@ -464,6 +464,7 @@ OBJS-$(CONFIG_RTMPTS_PROTOCOL) += rtmpproto.o rtmppkt.o
OBJS-$(CONFIG_RTP_PROTOCOL) += rtpproto.o
OBJS-$(CONFIG_SCTP_PROTOCOL) += sctp.o
OBJS-$(CONFIG_SRTP_PROTOCOL) += srtpproto.o srtp.o
+OBJS-$(CONFIG_SUBFILE_PROTOCOL) += subfile.o
OBJS-$(CONFIG_TCP_PROTOCOL) += tcp.o
OBJS-$(CONFIG_TLS_PROTOCOL) += tls.o
OBJS-$(CONFIG_UDP_PROTOCOL) += udp.o
diff --git a/libavformat/allformats.c b/libavformat/allformats.c
index 0e70b6e..16a3ae3 100644
--- a/libavformat/allformats.c
+++ b/libavformat/allformats.c
@@ -338,6 +338,7 @@ void av_register_all(void)
REGISTER_PROTOCOL(RTP, rtp);
REGISTER_PROTOCOL(SCTP, sctp);
REGISTER_PROTOCOL(SRTP, srtp);
+ REGISTER_PROTOCOL(SUBFILE, subfile);
REGISTER_PROTOCOL(TCP, tcp);
REGISTER_PROTOCOL(TLS, tls);
REGISTER_PROTOCOL(UDP, udp);
diff --git a/libavformat/subfile.c b/libavformat/subfile.c
new file mode 100644
index 0000000..e683be5
--- /dev/null
+++ b/libavformat/subfile.c
@@ -0,0 +1,145 @@
+/*
+ * Copyright (c) 2014 Nicolas George
+ *
+ * This file is part of FFmpeg.
+ *
+ * FFmpeg is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public License
+ * as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * FFmpeg 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 Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public License
+ * along with FFmpeg; if not, write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
+ */
+
+#include "libavutil/avassert.h"
+#include "libavutil/avstring.h"
+#include "libavutil/opt.h"
+#include "avformat.h"
+#include "url.h"
+
+typedef struct SubfileContext {
+ const AVClass *class;
+ URLContext *h;
+ int64_t start;
+ int64_t end;
+ int64_t pos;
+} SubfileContext;
+
+#define OFFSET(field) offsetof(SubfileContext, field)
+#define D AV_OPT_FLAG_DECODING_PARAM
+
+static const AVOption subfile_options[] = {
+ { "start", "start offset", OFFSET(start), AV_OPT_TYPE_INT64, {.i64 = 0}, 0, INT64_MAX, D },
+ { "end", "end offset", OFFSET(end), AV_OPT_TYPE_INT64, {.i64 = 0}, 0, INT64_MAX, D },
+ { NULL }
+};
+
+#undef OFFSET
+#undef D
+
+static const AVClass subfile_class = {
+ .class_name = "subfile",
+ .item_name = av_default_item_name,
+ .option = subfile_options,
+ .version = LIBAVUTIL_VERSION_INT,
+};
+
+static int slave_seek(URLContext *h)
+{
+ SubfileContext *c = h->priv_data;
+ int64_t ret;
+
+ if ((ret = ffurl_seek(c->h, c->pos, SEEK_SET)) != c->pos) {
+ if (ret >= 0)
+ ret = AVERROR_BUG;
+ av_log(h, AV_LOG_ERROR, "Impossible to seek in file: %s\n",
+ av_err2str(ret));
+ return ret;
+ }
+ return 0;
+}
+
+static int subfile_open(URLContext *h, const char *filename, int flags,
+ AVDictionary **options)
+{
+ SubfileContext *c = h->priv_data;
+ int ret;
+
+ if (c->end <= c->start) {
+ av_log(h, AV_LOG_ERROR, "end before start\n");
+ return AVERROR(EINVAL);
+ }
+ av_strstart(filename, "subfile:", &filename);
+ ret = ffurl_open(&c->h, filename, flags, &h->interrupt_callback, options);
+ if (ret < 0)
+ return ret;
+ c->pos = c->start;
+ if ((ret = slave_seek(h)) < 0) {
+ ffurl_close(c->h);
+ return ret;
+ }
+ return 0;
+}
+
+static int subfile_close(URLContext *h)
+{
+ SubfileContext *c = h->priv_data;
+ return ffurl_close(c->h);
+}
+
+static int subfile_read(URLContext *h, unsigned char *buf, int size)
+{
+ SubfileContext *c = h->priv_data;
+ int64_t rest = c->end - c->pos;
+ int ret;
+
+ if (rest < 0)
+ return AVERROR_EOF;
+ size = FFMIN(size, rest);
+ ret = ffurl_read(c->h, buf, size);
+ if (ret >= 0)
+ c->pos += ret;
+ return ret;
+}
+
+static int64_t subfile_seek(URLContext *h, int64_t pos, int whence)
+{
+ SubfileContext *c = h->priv_data;
+ int ret;
+
+ if (whence == AVSEEK_SIZE)
+ return c->end - c->start;
+ switch (whence) {
+ case SEEK_SET:
+ c->pos = c->start + pos;
+ break;
+ case SEEK_CUR:
+ c->pos += pos;
+ break;
+ case SEEK_END:
+ c->pos = c->end + c->pos;
+ break;
+ default:
+ return AVERROR(EINVAL);
+ }
+ if ((ret = slave_seek(h)) < 0)
+ return ret;
+ return c->pos - c->start;
+}
+
+URLProtocol ff_subfile_protocol = {
+ .name = "subfile",
+ .url_open2 = subfile_open,
+ .url_read = subfile_read,
+ .url_seek = subfile_seek,
+ .url_close = subfile_close,
+ .priv_data_size = sizeof(SubfileContext),
+ .priv_data_class = &subfile_class,
+};
diff --git a/libavformat/version.h b/libavformat/version.h
index 9f0695c..f9fc9d8 100644
--- a/libavformat/version.h
+++ b/libavformat/version.h
@@ -30,7 +30,7 @@
#include "libavutil/version.h"
#define LIBAVFORMAT_VERSION_MAJOR 55
-#define LIBAVFORMAT_VERSION_MINOR 33
+#define LIBAVFORMAT_VERSION_MINOR 34
#define LIBAVFORMAT_VERSION_MICRO 100
#define LIBAVFORMAT_VERSION_INT AV_VERSION_INT(LIBAVFORMAT_VERSION_MAJOR, \
--
1.8.5.3
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