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mpeg4_unpack_bframes_bsf.c
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1 /*
2  * Bitstream filter for unpacking DivX-style packed B-frames in MPEG-4 (divx_packed)
3  * Copyright (c) 2015 Andreas Cadhalpun <Andreas.Cadhalpun@googlemail.com>
4  *
5  * This file is part of FFmpeg.
6  *
7  * FFmpeg is free software; you can redistribute it and/or
8  * modify it under the terms of the GNU Lesser General Public
9  * License as published by the Free Software Foundation; either
10  * version 2.1 of the License, or (at your option) any later version.
11  *
12  * FFmpeg is distributed in the hope that it will be useful,
13  * but WITHOUT ANY WARRANTY; without even the implied warranty of
14  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
15  * Lesser General Public License for more details.
16  *
17  * You should have received a copy of the GNU Lesser General Public
18  * License along with FFmpeg; if not, write to the Free Software
19  * Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
20  */
21 
22 #include "avcodec.h"
23 #include "bsf.h"
24 #include "mpeg4video.h"
25 
26 typedef struct UnpackBFramesBSFContext {
29 
30 /* search next start code */
31 static unsigned int find_startcode(const uint8_t *buf, int buf_size, int *pos)
32 {
33  unsigned int startcode = 0xFF;
34 
35  for (; *pos < buf_size;) {
36  startcode = ((startcode << 8) | buf[*pos]) & 0xFFFFFFFF;
37  *pos +=1;
38  if ((startcode & 0xFFFFFF00) != 0x100)
39  continue; /* no startcode */
40  return startcode;
41  }
42 
43  return 0;
44 }
45 
46 /* determine the position of the packed marker in the userdata,
47  * the number of VOPs and the position of the second VOP */
48 static void scan_buffer(const uint8_t *buf, int buf_size,
49  int *pos_p, int *nb_vop, int *pos_vop2) {
50  unsigned int startcode;
51  int pos, i;
52 
53  for (pos = 0; pos < buf_size;) {
54  startcode = find_startcode(buf, buf_size, &pos);
55 
56  if (startcode == USER_DATA_STARTCODE && pos_p) {
57  /* check if the (DivX) userdata string ends with 'p' (packed) */
58  for (i = 0; i < 255 && pos + i + 1 < buf_size; i++) {
59  if (buf[pos + i] == 'p' && buf[pos + i + 1] == '\0') {
60  *pos_p = pos + i;
61  break;
62  }
63  }
64  } else if (startcode == VOP_STARTCODE && nb_vop) {
65  *nb_vop += 1;
66  if (*nb_vop == 2 && pos_vop2) {
67  *pos_vop2 = pos - 4; /* subtract 4 bytes startcode */
68  }
69  }
70  }
71 }
72 
74 {
76  int pos_p = -1, nb_vop = 0, pos_vop2 = -1, ret = 0;
77  AVPacket *in;
78 
79  ret = ff_bsf_get_packet(ctx, &in);
80  if (ret < 0)
81  return ret;
82 
83  scan_buffer(in->data, in->size, &pos_p, &nb_vop, &pos_vop2);
84  av_log(ctx, AV_LOG_DEBUG, "Found %d VOP startcode(s) in this packet.\n", nb_vop);
85 
86  if (pos_vop2 >= 0) {
87  if (s->b_frame->data) {
89  "Missing one N-VOP packet, discarding one B-frame.\n");
91  }
92  /* store the packed B-frame in the BSFContext */
93  ret = av_packet_ref(s->b_frame, in);
94  if (ret < 0) {
95  goto fail;
96  }
97  s->b_frame->size -= pos_vop2;
98  s->b_frame->data += pos_vop2;
99  }
100 
101  if (nb_vop > 2) {
102  av_log(ctx, AV_LOG_WARNING,
103  "Found %d VOP headers in one packet, only unpacking one.\n", nb_vop);
104  }
105 
106  if (nb_vop == 1 && s->b_frame->data) {
107  /* use frame from BSFContext */
108  av_packet_move_ref(out, s->b_frame);
109 
110  /* use properties from current input packet */
111  ret = av_packet_copy_props(out, in);
112  if (ret < 0) {
113  goto fail;
114  }
115 
116  if (in->size <= MAX_NVOP_SIZE) {
117  /* N-VOP */
118  av_log(ctx, AV_LOG_DEBUG, "Skipping N-VOP.\n");
119  } else {
120  /* copy packet into BSFContext */
121  av_packet_move_ref(s->b_frame, in);
122  }
123  } else if (nb_vop >= 2) {
124  /* use first frame of the packet */
125  av_packet_move_ref(out, in);
126  out->size = pos_vop2;
127  } else if (pos_p >= 0) {
128  ret = av_packet_make_writable(in);
129  if (ret < 0)
130  goto fail;
131  av_log(ctx, AV_LOG_DEBUG, "Updating DivX userdata (remove trailing 'p').\n");
132  av_packet_move_ref(out, in);
133  /* remove 'p' (packed) from the end of the (DivX) userdata string */
134  out->data[pos_p] = '\0';
135  } else {
136  /* copy packet */
137  av_packet_move_ref(out, in);
138  }
139 
140 fail:
141  if (ret < 0)
142  av_packet_unref(out);
143  av_packet_free(&in);
144 
145  return ret;
146 }
147 
149 {
151 
152  s->b_frame = av_packet_alloc();
153  if (!s->b_frame)
154  return AVERROR(ENOMEM);
155 
156  if (ctx->par_in->extradata) {
157  int pos_p_ext = -1;
158  scan_buffer(ctx->par_in->extradata, ctx->par_in->extradata_size, &pos_p_ext, NULL, NULL);
159  if (pos_p_ext >= 0) {
160  av_log(ctx, AV_LOG_DEBUG,
161  "Updating DivX userdata (remove trailing 'p') in extradata.\n");
162  ctx->par_out->extradata[pos_p_ext] = '\0';
163  }
164  }
165 
166  return 0;
167 }
168 
170 {
172  av_packet_free(&ctx->b_frame);
173 }
174 
175 static const enum AVCodecID codec_ids[] = {
177 };
178 
180  .name = "mpeg4_unpack_bframes",
181  .priv_data_size = sizeof(UnpackBFramesBSFContext),
185  .codec_ids = codec_ids,
186 };
#define NULL
Definition: coverity.c:32
AVCodecParameters * par_out
Parameters of the output stream.
Definition: avcodec.h:5723
static void mpeg4_unpack_bframes_close(AVBSFContext *bsfc)
#define AV_LOG_WARNING
Something somehow does not look correct.
Definition: log.h:182
static av_cold int init(AVCodecContext *avctx)
Definition: avrndec.c:35
static int mpeg4_unpack_bframes_filter(AVBSFContext *ctx, AVPacket *out)
The bitstream filter state.
Definition: avcodec.h:5689
int size
Definition: avcodec.h:1433
void * priv_data
Opaque filter-specific private data.
Definition: avcodec.h:5710
#define USER_DATA_STARTCODE
Definition: mpeg4video.h:62
static void filter(int16_t *output, ptrdiff_t out_stride, int16_t *low, ptrdiff_t low_stride, int16_t *high, ptrdiff_t high_stride, int len, int clip)
Definition: cfhd.c:153
void av_packet_free(AVPacket **pkt)
Free the packet, if the packet is reference counted, it will be unreferenced first.
Definition: avpacket.c:62
uint8_t
const AVBitStreamFilter ff_mpeg4_unpack_bframes_bsf
#define VOP_STARTCODE
Definition: mpeg4video.h:65
const char * name
Definition: avcodec.h:5739
uint8_t * data
Definition: avcodec.h:1432
void av_packet_move_ref(AVPacket *dst, AVPacket *src)
Move every field in src to dst and reset src.
Definition: avpacket.c:647
#define av_log(a,...)
int av_packet_ref(AVPacket *dst, const AVPacket *src)
Setup a new reference to the data described by a given packet.
Definition: avpacket.c:601
int av_packet_make_writable(AVPacket *pkt)
Create a writable reference for the data described by a given packet, avoiding data copy if possible...
Definition: avpacket.c:673
AVCodecID
Identify the syntax and semantics of the bitstream.
Definition: avcodec.h:215
#define AVERROR(e)
Definition: error.h:43
#define AV_LOG_DEBUG
Stuff which is only useful for libav* developers.
Definition: log.h:197
#define fail()
Definition: checkasm.h:117
int extradata_size
Size of the extradata content in bytes.
Definition: avcodec.h:3904
int av_packet_copy_props(AVPacket *dst, const AVPacket *src)
Copy only "properties" fields from src to dst.
Definition: avpacket.c:558
static unsigned int find_startcode(const uint8_t *buf, int buf_size, int *pos)
AVFormatContext * ctx
Definition: movenc.c:48
static int mpeg4_unpack_bframes_init(AVBSFContext *ctx)
#define s(width, name)
Definition: cbs_vp9.c:257
Libavcodec external API header.
void av_packet_unref(AVPacket *pkt)
Wipe the packet.
Definition: avpacket.c:592
uint8_t pi<< 24) CONV_FUNC_GROUP(AV_SAMPLE_FMT_FLT, float, AV_SAMPLE_FMT_U8, uint8_t,(*(constuint8_t *) pi-0x80)*(1.0f/(1<< 7))) CONV_FUNC_GROUP(AV_SAMPLE_FMT_DBL, double, AV_SAMPLE_FMT_U8, uint8_t,(*(constuint8_t *) pi-0x80)*(1.0/(1<< 7))) CONV_FUNC_GROUP(AV_SAMPLE_FMT_U8, uint8_t, AV_SAMPLE_FMT_S16, int16_t,(*(constint16_t *) pi >>8)+0x80) CONV_FUNC_GROUP(AV_SAMPLE_FMT_FLT, float, AV_SAMPLE_FMT_S16, int16_t,*(constint16_t *) pi *(1.0f/(1<< 15))) CONV_FUNC_GROUP(AV_SAMPLE_FMT_DBL, double, AV_SAMPLE_FMT_S16, int16_t,*(constint16_t *) pi *(1.0/(1<< 15))) CONV_FUNC_GROUP(AV_SAMPLE_FMT_U8, uint8_t, AV_SAMPLE_FMT_S32, int32_t,(*(constint32_t *) pi >>24)+0x80) CONV_FUNC_GROUP(AV_SAMPLE_FMT_FLT, float, AV_SAMPLE_FMT_S32, int32_t,*(constint32_t *) pi *(1.0f/(1U<< 31))) CONV_FUNC_GROUP(AV_SAMPLE_FMT_DBL, double, AV_SAMPLE_FMT_S32, int32_t,*(constint32_t *) pi *(1.0/(1U<< 31))) CONV_FUNC_GROUP(AV_SAMPLE_FMT_U8, uint8_t, AV_SAMPLE_FMT_FLT, float, av_clip_uint8(lrintf(*(constfloat *) pi *(1<< 7))+0x80)) CONV_FUNC_GROUP(AV_SAMPLE_FMT_S16, int16_t, AV_SAMPLE_FMT_FLT, float, av_clip_int16(lrintf(*(constfloat *) pi *(1<< 15)))) CONV_FUNC_GROUP(AV_SAMPLE_FMT_S32, int32_t, AV_SAMPLE_FMT_FLT, float, av_clipl_int32(llrintf(*(constfloat *) pi *(1U<< 31)))) CONV_FUNC_GROUP(AV_SAMPLE_FMT_U8, uint8_t, AV_SAMPLE_FMT_DBL, double, av_clip_uint8(lrint(*(constdouble *) pi *(1<< 7))+0x80)) CONV_FUNC_GROUP(AV_SAMPLE_FMT_S16, int16_t, AV_SAMPLE_FMT_DBL, double, av_clip_int16(lrint(*(constdouble *) pi *(1<< 15)))) CONV_FUNC_GROUP(AV_SAMPLE_FMT_S32, int32_t, AV_SAMPLE_FMT_DBL, double, av_clipl_int32(llrint(*(constdouble *) pi *(1U<< 31))))#defineSET_CONV_FUNC_GROUP(ofmt, ifmt) staticvoidset_generic_function(AudioConvert *ac){}voidff_audio_convert_free(AudioConvert **ac){if(!*ac) return;ff_dither_free(&(*ac) ->dc);av_freep(ac);}AudioConvert *ff_audio_convert_alloc(AVAudioResampleContext *avr, enumAVSampleFormatout_fmt, enumAVSampleFormatin_fmt, intchannels, intsample_rate, intapply_map){AudioConvert *ac;intin_planar, out_planar;ac=av_mallocz(sizeof(*ac));if(!ac) returnNULL;ac->avr=avr;ac->out_fmt=out_fmt;ac->in_fmt=in_fmt;ac->channels=channels;ac->apply_map=apply_map;if(avr->dither_method!=AV_RESAMPLE_DITHER_NONE &&av_get_packed_sample_fmt(out_fmt)==AV_SAMPLE_FMT_S16 &&av_get_bytes_per_sample(in_fmt)>2){ac->dc=ff_dither_alloc(avr, out_fmt, in_fmt, channels, sample_rate, apply_map);if(!ac->dc){av_free(ac);returnNULL;}returnac;}in_planar=ff_sample_fmt_is_planar(in_fmt, channels);out_planar=ff_sample_fmt_is_planar(out_fmt, channels);if(in_planar==out_planar){ac->func_type=CONV_FUNC_TYPE_FLAT;ac->planes=in_planar?ac->channels:1;}elseif(in_planar) ac->func_type=CONV_FUNC_TYPE_INTERLEAVE;elseac->func_type=CONV_FUNC_TYPE_DEINTERLEAVE;set_generic_function(ac);if(ARCH_AARCH64) ff_audio_convert_init_aarch64(ac);if(ARCH_ARM) ff_audio_convert_init_arm(ac);if(ARCH_X86) ff_audio_convert_init_x86(ac);returnac;}intff_audio_convert(AudioConvert *ac, AudioData *out, AudioData *in){intuse_generic=1;intlen=in->nb_samples;intp;if(ac->dc){av_log(ac->avr, AV_LOG_TRACE,"%dsamples-audio_convert:%sto%s(dithered)\n", len, av_get_sample_fmt_name(ac->in_fmt), av_get_sample_fmt_name(ac->out_fmt));returnff_convert_dither(ac-> in
void * buf
Definition: avisynth_c.h:690
static void scan_buffer(const uint8_t *buf, int buf_size, int *pos_p, int *nb_vop, int *pos_vop2)
static enum AVCodecID codec_ids[]
int ff_bsf_get_packet(AVBSFContext *ctx, AVPacket **pkt)
Called by the bitstream filters to get the next packet for filtering.
Definition: bsf.c:206
AVPacket * av_packet_alloc(void)
Allocate an AVPacket and set its fields to default values.
Definition: avpacket.c:51
uint8_t * extradata
Extra binary data needed for initializing the decoder, codec-dependent.
Definition: avcodec.h:3900
FILE * out
Definition: movenc.c:54
This structure stores compressed data.
Definition: avcodec.h:1409
AVCodecParameters * par_in
Parameters of the input stream.
Definition: avcodec.h:5717
#define MAX_NVOP_SIZE
Definition: mpeg4video.h:72