On Fri, Apr 12, 2019 at 07:15:49AM +0530, Shivam wrote:
> On 4/10/19 10:05 PM, Michael Niedermayer wrote:
> >On Tue, Apr 09, 2019 at 11:50:16PM +0530, Shivam Goyal wrote:
> >>lavf/flv: Add XV (Xunlei Video) Support.
> >>
> >>Fixes ticket #3720.
> >>
> >>
> >>
> >> Changelog | 1
> >> libavformat/Makefile | 1
> >> libavformat/allformats.c | 1
> >> libavformat/flvdec.c | 86
> >> +++++++++++++++++++++++++++++++++++++++++++++++
> >> libavformat/version.h | 2 -
> >> 5 files changed, 90 insertions(+), 1 deletion(-)
> >>c221c019d4dcd7063828c54567b8fc7c905b211b added_xv_support_v6.patch
> >> From 605dc262abf948813c26d58f51d5e2d7f498d9cd Mon Sep 17 00:00:00 2001
> >>From: Shivam Goyal<shi...@iitk.ac.in>
> >>Date: Tue, 9 Apr 2019 23:36:27 +0530
> >>Subject: [PATCH] lavf/flv: Add XV (Xunlei Video) Support. Fixes ticket
> >>#3720.
> >>
> >>---
> >> Changelog | 1 +
> >> libavformat/Makefile | 1 +
> >> libavformat/allformats.c | 1 +
> >> libavformat/flvdec.c | 86 ++++++++++++++++++++++++++++++++++++++++
> >> libavformat/version.h | 2 +-
> >> 5 files changed, 90 insertions(+), 1 deletion(-)
> >>
> >>diff --git a/Changelog b/Changelog
> >>index 8c866cd0c2..8caaab53c2 100644
> >>--- a/Changelog
> >>+++ b/Changelog
> >>@@ -22,6 +22,7 @@ version <next>:
> >> - removed libndi-newtek
> >> - agm decoder
> >> - KUX demuxer
> >>+- XV (Xunlei Video) demuxer
> >> version 4.1:
> >>diff --git a/libavformat/Makefile b/libavformat/Makefile
> >>index 99be60d184..e090c051f1 100644
> >>--- a/libavformat/Makefile
> >>+++ b/libavformat/Makefile
> >>@@ -561,6 +561,7 @@ OBJS-$(CONFIG_WV_MUXER) += wvenc.o
> >>wv.o apetag.o img2.o
> >> OBJS-$(CONFIG_XA_DEMUXER) += xa.o
> >> OBJS-$(CONFIG_XBIN_DEMUXER) += bintext.o sauce.o
> >> OBJS-$(CONFIG_XMV_DEMUXER) += xmv.o
> >>+OBJS-$(CONFIG_XV_DEMUXER) += flvdec.o
> >> OBJS-$(CONFIG_XVAG_DEMUXER) += xvag.o
> >> OBJS-$(CONFIG_XWMA_DEMUXER) += xwma.o
> >> OBJS-$(CONFIG_YOP_DEMUXER) += yop.o
> >>diff --git a/libavformat/allformats.c b/libavformat/allformats.c
> >>index d316a0529a..b499186071 100644
> >>--- a/libavformat/allformats.c
> >>+++ b/libavformat/allformats.c
> >>@@ -456,6 +456,7 @@ extern AVOutputFormat ff_wv_muxer;
> >> extern AVInputFormat ff_xa_demuxer;
> >> extern AVInputFormat ff_xbin_demuxer;
> >> extern AVInputFormat ff_xmv_demuxer;
> >>+extern AVInputFormat ff_xv_demuxer;
> >> extern AVInputFormat ff_xvag_demuxer;
> >> extern AVInputFormat ff_xwma_demuxer;
> >> extern AVInputFormat ff_yop_demuxer;
> >>diff --git a/libavformat/flvdec.c b/libavformat/flvdec.c
> >>index b531a39adc..a56f5b448a 100644
> >>--- a/libavformat/flvdec.c
> >>+++ b/libavformat/flvdec.c
> >>@@ -127,6 +127,19 @@ static int kux_probe(const AVProbeData *p)
> >> return 0;
> >> }
> >>+static int xv_probe(const AVProbeData *p)
> >>+{
> >>+ const uint8_t *d = p->buf;
> >>+
> >>+ if (d[0] == 'X' &&
> >>+ d[1] == 'L' &&
> >>+ d[2] == 'V' &&
> >>+ d[3] == 'F') {
> >>+ return AVPROBE_SCORE_EXTENSION + 1;
> >>+ }
> >>+ return 0;
> >>+}
> >>+
> >> static void add_keyframes_index(AVFormatContext *s)
> >> {
> >> FLVContext *flv = s->priv_data;
> >>@@ -459,6 +472,12 @@ static int parse_keyframes_index(AVFormatContext *s,
> >>AVIOContext *ioc, int64_t m
> >> }
> >> }
> >>+ if (!strcmp(s->iformat->name , "xv")) {
> >>+ for (i = 0; i < FFMIN(2,fileposlen); i++) {
> >>+ filepositions[i] += 0x200000;
> >>+ }
> >>+ }
> >>+
> >> if (timeslen == fileposlen && fileposlen>1 && max_pos <=
> >> filepositions[0]) {
> >> for (i = 0; i < FFMIN(2,fileposlen); i++) {
> >> flv->validate_index[i].pos = filepositions[i];
> >>@@ -783,6 +802,52 @@ static int flv_read_header(AVFormatContext *s)
> >> return 0;
> >> }
> >>+static int xv_read_header(AVFormatContext *s)
> >>+{
> >>+ int flags;
> >>+ FLVContext *xv = s->priv_data;
> >>+ AVIOContext *ic = s->pb;
> >>+ int offset;
> >>+ int rot;
> >>+ int i;
> >>+ int64_t pos;
> >>+
> >>+ //Find the rot value for rotating the bytes
> >>+ avio_skip(ic, 0x200000);
> >>+ rot = 0x46 - avio_r8(ic);
> >>+
> >>+ avio_skip(ic, 3);
> >>+
> >>+ flags = (avio_r8(ic) + rot) & 0xff;
> >>+
> >>+ xv->missing_streams = flags & (FLV_HEADER_FLAG_HASVIDEO |
> >>FLV_HEADER_FLAG_HASAUDIO);
> >>+
> >>+ s->ctx_flags |= AVFMTCTX_NOHEADER;
> >>+
> >>+ offset = ((avio_r8(ic) + rot & 0xff) << 24 |
> >>+ (avio_r8(ic) + rot & 0xff) << 16 |
> >>+ (avio_r8(ic) + rot & 0xff) << 8 |
> >>+ (avio_r8(ic) + rot & 0xff)) + 0x200000;
> >>+
> >>+ avio_seek(ic, offset + 4, SEEK_SET);
> >>+
> >>+
> >>+ // Will modify the current buffer, as only
> >>+ // the bytes from 0x200000 to 0x200400 are needed to decode
> >>+ pos = ic->pos + ic->buf_ptr - ic->buf_end;
> >>+ for (i = 0; i < 0x400; i++) {
> >>+ if (pos >= 0x200400) break;
> >>+ ic->buf_ptr[i] = (ic->buf_ptr[i] + rot) & 0xff;
> >>+ pos++;
> >>+ }
> >the demuxer should not manipulate the protocols /avio internal buffer.
> >This would make the demuxer depend on how this buffer is implemented.
> >Also the data that needs changes may not be in the buffer but be read
> >later i think-
> >It would be quite annoying for maintaince if changing the internal
> >AVIO code would require updating the implementations of demuxers
> >
> >[...]
> >
>
> Yeah, I realise that this would be hard to maintain. and would not work if
> we change the structure of the AVIOContaxt.
>
> But, what is the best solution for this. I also tried to pass the avio read
> calls back to a custom function. But then i don't have access to a rot
> value, which is needed to rotate the bytes.The avio stuff has a opaque pointer that allows you to access a structure of your choosing when its your own avio context. This struct could contain rot and the avio context for the parent to pass calls on > > Or, could you help me in providing some examples, where this kind of problem > arised in any other demuxer. iam not sure but maybe git grep avio_alloc_context points to something usefull [...] -- Michael GnuPG fingerprint: 9FF2128B147EF6730BADF133611EC787040B0FAB Those who would give up essential Liberty, to purchase a little temporary Safety, deserve neither Liberty nor Safety -- Benjamin Franklin
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