From c2341b8596fbd3736a1b21cc0be4ac5997e14b8c Mon Sep 17 00:00:00 2001
From: Alex Converse <alex.converse@gmail.com>
Date: Wed, 19 May 2010 20:18:40 +0000
Subject: [PATCH] Add a chomp BSF to consume zero padding at the end of a
 packet.

Originally committed as revision 23196 to svn://svn.ffmpeg.org/ffmpeg/trunk
---
 libavcodec/Makefile    |  1 +
 libavcodec/allcodecs.c |  1 +
 libavcodec/chomp_bsf.c | 47 ++++++++++++++++++++++++++++++++++++++++++
 3 files changed, 49 insertions(+)
 create mode 100644 libavcodec/chomp_bsf.c

diff --git a/libavcodec/Makefile b/libavcodec/Makefile
index 03acb3c316..a112850d68 100644
--- a/libavcodec/Makefile
+++ b/libavcodec/Makefile
@@ -577,6 +577,7 @@ OBJS-$(CONFIG_VP3_PARSER)              += vp3_parser.o
 
 # bitstream filters
 OBJS-$(CONFIG_AAC_ADTSTOASC_BSF)          += aac_adtstoasc_bsf.o
+OBJS-$(CONFIG_CHOMP_BSF)                  += chomp_bsf.o
 OBJS-$(CONFIG_DUMP_EXTRADATA_BSF)         += dump_extradata_bsf.o
 OBJS-$(CONFIG_H264_MP4TOANNEXB_BSF)       += h264_mp4toannexb_bsf.o
 OBJS-$(CONFIG_IMX_DUMP_HEADER_BSF)        += imx_dump_header_bsf.o
diff --git a/libavcodec/allcodecs.c b/libavcodec/allcodecs.c
index e02334674f..d7efd119b5 100644
--- a/libavcodec/allcodecs.c
+++ b/libavcodec/allcodecs.c
@@ -375,6 +375,7 @@ void avcodec_register_all(void)
 
     /* bitstream filters */
     REGISTER_BSF     (AAC_ADTSTOASC, aac_adtstoasc);
+    REGISTER_BSF     (CHOMP, chomp);
     REGISTER_BSF     (DUMP_EXTRADATA, dump_extradata);
     REGISTER_BSF     (H264_MP4TOANNEXB, h264_mp4toannexb);
     REGISTER_BSF     (IMX_DUMP_HEADER, imx_dump_header);
diff --git a/libavcodec/chomp_bsf.c b/libavcodec/chomp_bsf.c
new file mode 100644
index 0000000000..caf1ff9ac4
--- /dev/null
+++ b/libavcodec/chomp_bsf.c
@@ -0,0 +1,47 @@
+/*
+ * Chomp bitstream filter
+ * Copyright (c) 2010 Alex Converse <alex.converse@gmail.com>
+ *
+ * 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 "avcodec.h"
+#include "internal.h"
+
+static int chomp_filter(AVBitStreamFilterContext *bsfc,
+                        AVCodecContext *avctx, const char *args,
+                        uint8_t  **poutbuf, int *poutbuf_size,
+                        const uint8_t *buf, int      buf_size,
+                        int keyframe)
+{
+    while (buf_size > 0 && !buf[buf_size-1])
+        buf_size--;
+
+    *poutbuf = (uint8_t*) buf;
+    *poutbuf_size = buf_size;
+
+    return 0;
+}
+
+/**
+ * This filter removes a string of \0 bytes from the end of a packet.
+ */
+AVBitStreamFilter chomp_bsf = {
+    "chomp",
+    0,
+    chomp_filter,
+};