@@ -13,6 +13,7 @@ version <next>:

 - Intel QSV-accelerated H.264 encoding

 - MMAL-accelerated H.264 decoding

 - basic APNG encoder and muxer

+- unpack DivX-style packed B-frames in MPEG-4 bitstream filter

 version 2.6:

@@ -139,6 +139,26 @@ ffmpeg -i frame_%d.jpg -c:v copy rotated.avi

 @section mp3_header_decompress

+@section mpeg4_unpack_bframes

+

+Unpack DivX-style packed B-frames.

+

+DivX-style packed B-frames are not valid MPEG-4 and were only a

+workaround for the broken Video for Windows subsystem.

+They use more space, can cause minor AV sync issues, require more

+CPU power to decode (unless the player has some decoded picture queue

+to compensate the 2,0,2,0 frame per packet style) and cause

+trouble if copied into a standard container like mp4 or mpeg-ps/ts,

+because MPEG-4 decoders may not be able to decode them, since they are

+not valid MPEG-4.

+

+For example to fix an AVI file containing an MPEG-4 stream with

+DivX-style packed B-frames using @command{ffmpeg}, you can use the command:

+

+@example

+ffmpeg -i INPUT.avi -codec copy -bsf:v mpeg4_unpack_bframes OUTPUT.avi

+@end example

+

 @section noise

 Damages the contents of packets without damaging the container. Can be

@@ -841,6 +841,7 @@ OBJS-$(CONFIG_H264_MP4TOANNEXB_BSF)       += h264_mp4toannexb_bsf.o

 OBJS-$(CONFIG_IMX_DUMP_HEADER_BSF)        += imx_dump_header_bsf.o

 OBJS-$(CONFIG_MJPEG2JPEG_BSF)             += mjpeg2jpeg_bsf.o

 OBJS-$(CONFIG_MJPEGA_DUMP_HEADER_BSF)     += mjpega_dump_header_bsf.o

+OBJS-$(CONFIG_MPEG4_UNPACK_BFRAMES_BSF)   += mpeg4_unpack_bframes_bsf.o

 OBJS-$(CONFIG_MOV2TEXTSUB_BSF)            += movsub_bsf.o

 OBJS-$(CONFIG_MP3_HEADER_DECOMPRESS_BSF)  += mp3_header_decompress_bsf.o \

                                              mpegaudiodata.o

@@ -605,6 +605,7 @@ void avcodec_register_all(void)

     REGISTER_BSF(MJPEG2JPEG,            mjpeg2jpeg);

     REGISTER_BSF(MJPEGA_DUMP_HEADER,    mjpega_dump_header);

     REGISTER_BSF(MP3_HEADER_DECOMPRESS, mp3_header_decompress);

+    REGISTER_BSF(MPEG4_UNPACK_BFRAMES,  mpeg4_unpack_bframes);

     REGISTER_BSF(MOV2TEXTSUB,           mov2textsub);

     REGISTER_BSF(NOISE,                 noise);

     REGISTER_BSF(REMOVE_EXTRADATA,      remove_extradata);

new file mode 100644

@@ -0,0 +1,194 @@

+/*

+ * Bitstream filter for unpacking DivX-style packed B-frames in MPEG-4 (divx_packed)

+ * Copyright (c) 2015 Andreas Cadhalpun <Andreas.Cadhalpun@googlemail.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 "mpeg4video.h"

+

+typedef struct UnpackBFramesBSFContext {

+    uint8_t *b_frame_buf;

+    int      b_frame_buf_size;

+    int      updated_extradata;

+} UnpackBFramesBSFContext;

+

+/* search next start code */

+static unsigned int find_startcode(const uint8_t *buf, int buf_size, int *pos)

+{

+    unsigned int startcode = 0xFF;

+

+    for (; *pos < buf_size;) {

+        startcode = ((startcode << 8) | buf[*pos]) & 0xFFFFFFFF;

+        *pos +=1;

+        if ((startcode & 0xFFFFFF00) != 0x100)

+            continue;  /* no startcode */

+        return startcode;

+    }

+

+    return 0;

+}

+

+/* determine the position of the packed marker in the userdata,

+ * the number of VOPs and the position of the second VOP */

+static void scan_buffer(const uint8_t *buf, int buf_size,

+                        int *pos_p, int *nb_vop, int *pos_vop2) {

+    unsigned int startcode;

+    int pos, i;

+

+    for (pos = 0; pos < buf_size;) {

+        startcode = find_startcode(buf, buf_size, &pos);

+

+        if (startcode == USER_DATA_STARTCODE && pos_p) {

+            /* check if the (DivX) userdata string ends with 'p' (packed) */

+            for (i = 0; i < 255 && pos + i + 1 < buf_size; i++) {

+                if (buf[pos + i] == 'p' && buf[pos + i + 1] == '\0') {

+                    *pos_p = pos + i;

+                    break;

+                }

+            }

+        } else if (startcode == VOP_STARTCODE && nb_vop) {

+            *nb_vop += 1;

+            if (*nb_vop == 2 && pos_vop2) {

+                *pos_vop2 = pos - 4; /* subtract 4 bytes startcode */

+            }

+        }

+    }

+}

+

+/* allocate new buffer and copy size bytes from src */

+static uint8_t *create_new_buffer(const uint8_t *src, int size) {

+    uint8_t *dst = av_malloc(size + FF_INPUT_BUFFER_PADDING_SIZE);

+

+    if (dst) {

+        memcpy(dst, src, size);

+        memset(dst + size, 0, FF_INPUT_BUFFER_PADDING_SIZE);

+    }

+

+    return dst;

+}

+

+static int mpeg4_unpack_bframes_filter(AVBitStreamFilterContext *bsfc,

+                                       AVCodecContext *avctx, const char *args,

+                                       uint8_t  **poutbuf, int *poutbuf_size,

+                                       const uint8_t *buf, int      buf_size,

+                                       int keyframe)

+{

+    UnpackBFramesBSFContext *ctx = bsfc->priv_data;

+    int pos_p = -1, nb_vop = 0, pos_vop2 = -1, ret = 0;

+

+    if (avctx->codec_id != AV_CODEC_ID_MPEG4) {

+        av_log(avctx, AV_LOG_ERROR,

+               "The mpeg4_unpack_bframes bitstream filter is only useful for mpeg4.\n");

+        return AVERROR(EINVAL);

+    }

+

+    if (!ctx->updated_extradata && avctx->extradata) {

+        int pos_p_ext = -1;

+        scan_buffer(avctx->extradata, avctx->extradata_size, &pos_p_ext, NULL, NULL);

+        if (pos_p_ext >= 0) {

+            av_log(avctx, AV_LOG_DEBUG,

+                   "Updating DivX userdata (remove trailing 'p') in extradata.\n");

+            avctx->extradata[pos_p_ext] = '\0';

+        }

+        ctx->updated_extradata = 1;

+    }

+

+    scan_buffer(buf, buf_size, &pos_p, &nb_vop, &pos_vop2);

+    av_log(avctx, AV_LOG_DEBUG, "Found %d VOP startcode(s) in this packet.\n", nb_vop);

+

+    if (pos_vop2 >= 0) {

+        if (ctx->b_frame_buf) {

+            av_log(avctx, AV_LOG_WARNING,

+                   "Missing one N-VOP packet, discarding one B-frame.\n");

+            av_freep(&ctx->b_frame_buf);

+            ctx->b_frame_buf_size = 0;

+        }

+        /* store the packed B-frame in the BSFContext */

+        ctx->b_frame_buf_size = buf_size - pos_vop2;

+        ctx->b_frame_buf      = create_new_buffer(buf + pos_vop2, ctx->b_frame_buf_size);

+        if (!ctx->b_frame_buf) {

+            ctx->b_frame_buf_size = 0;

+            return AVERROR(ENOMEM);

+        }

+    }

+

+    if (nb_vop > 2) {

+        av_log(avctx, AV_LOG_WARNING,

+       "Found %d VOP headers in one packet, only unpacking one.\n", nb_vop);

+    }

+

+    if (nb_vop == 1 && ctx->b_frame_buf) {

+        /* use frame from BSFContext */

+        *poutbuf      = ctx->b_frame_buf;

+        *poutbuf_size = ctx->b_frame_buf_size;

+        /* the output buffer is distinct from the input buffer */

+        ret = 1;

+        if (buf_size <= MAX_NVOP_SIZE) {

+            /* N-VOP */

+            av_log(avctx, AV_LOG_DEBUG, "Skipping N-VOP.\n");

+            ctx->b_frame_buf      = NULL;

+            ctx->b_frame_buf_size = 0;

+        } else {

+            /* copy packet into BSFContext */

+            ctx->b_frame_buf_size = buf_size;

+            ctx->b_frame_buf      = create_new_buffer(buf , buf_size);

+            if (!ctx->b_frame_buf) {

+                ctx->b_frame_buf_size = 0;

+                av_freep(poutbuf);

+                *poutbuf_size = 0;

+                return AVERROR(ENOMEM);

+            }

+        }

+    } else if (nb_vop >= 2) {

+        /* use first frame of the packet */

+        *poutbuf      = (uint8_t *) buf;

+        *poutbuf_size = pos_vop2;

+    } else if (pos_p >= 0) {

+        av_log(avctx, AV_LOG_DEBUG, "Updating DivX userdata (remove trailing 'p').\n");

+        *poutbuf_size = buf_size;

+        *poutbuf      = create_new_buffer(buf, buf_size);

+        if (!*poutbuf) {

+            *poutbuf_size = 0;

+            return AVERROR(ENOMEM);

+        }

+        /* remove 'p' (packed) from the end of the (DivX) userdata string */

+        (*poutbuf)[pos_p] = '\0';

+        /* the output buffer is distinct from the input buffer */

+        ret = 1;

+    } else {

+        /* copy packet */

+        *poutbuf      = (uint8_t *) buf;

+        *poutbuf_size = buf_size;

+    }

+

+    return ret;

+}

+

+static void mpeg4_unpack_bframes_close(AVBitStreamFilterContext *bsfc)

+{

+    UnpackBFramesBSFContext *ctx = bsfc->priv_data;

+    av_freep(&ctx->b_frame_buf);

+}

+

+AVBitStreamFilter ff_mpeg4_unpack_bframes_bsf = {

+    .name           = "mpeg4_unpack_bframes",

+    .priv_data_size = sizeof(UnpackBFramesBSFContext),

+    .filter         = mpeg4_unpack_bframes_filter,

+    .close          = mpeg4_unpack_bframes_close

+};

@@ -29,7 +29,7 @@

 #include "libavutil/version.h"

 #define LIBAVCODEC_VERSION_MAJOR 56

-#define LIBAVCODEC_VERSION_MINOR  33

+#define LIBAVCODEC_VERSION_MINOR  34

 #define LIBAVCODEC_VERSION_MICRO 100

 #define LIBAVCODEC_VERSION_INT  AV_VERSION_INT(LIBAVCODEC_VERSION_MAJOR, \