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FFmpeg/libavcodec/cbs_mpeg2.c
Andreas Rheinhardt 14dd0a9057 avcodec/cbs: Avoid leaving the ... out in calls to variadic macros 
According to C99, there has to be at least one argument for every ...
in a variadic function-like macro. In practice most (all?) compilers also
allow to leave it completely out, but it is nevertheless required: In a
variadic macro "there shall be more arguments in the invocation than there
are parameters in the macro definition (excluding the ...)." (C99,
6.10.3.4).

CBS (not the framework itself, but the macros used in the
cbs_*_syntax_template.c files) relies on the compiler allowing to leave
a variadic macro argument out. This leads to warnings when compiling in
-pedantic mode, e.g. "warning: must specify at least one argument for
'...' parameter of variadic macro [-Wgnu-zero-variadic-macro-arguments]"
from Clang.

Most of these warnings can be easily avoided: The syntax_templates
mostly contain helper macros that expand to more complex variadic macros
and these helper macros often omit an argument for the .... Modifying
them to always expand to complex macros with an empty argument for the
... at the end fixes most of these warnings: The number of warnings went
down from 400 to 0 for cbs_av1, from 1114 to 32 for cbs_h2645, from 38 to
0 for cbs_jpeg, from 166 to 0 for cbs_mpeg2 and from 110 to 8 for cbs_vp9.

These eight remaining warnings for cbs_vp9 have been fixed by switching
to another macro in cbs_vp9_syntax_template: The fixed values for the
sync bytes as well as the trailing bits for byte-alignment are now read
via the fixed() macro (this also adds a check to ensure that trailing
bits are indeed zero as they have to be).

Reviewed-by: Mark Thompson <sw@jkqxz.net>
Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@gmail.com>
2020-04-12 23:23:49 +02:00

433 lines
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/*
* 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 "cbs.h"
#include "cbs_internal.h"
#include "cbs_mpeg2.h"
#include "internal.h"
#define HEADER(name) do { \
ff_cbs_trace_header(ctx, name); \
} while (0)
#define CHECK(call) do { \
err = (call); \
if (err < 0) \
return err; \
} while (0)
#define FUNC_NAME(rw, codec, name) cbs_ ## codec ## _ ## rw ## _ ## name
#define FUNC_MPEG2(rw, name) FUNC_NAME(rw, mpeg2, name)
#define FUNC(name) FUNC_MPEG2(READWRITE, name)
#define SUBSCRIPTS(subs, ...) (subs > 0 ? ((int[subs + 1]){ subs, __VA_ARGS__ }) : NULL)
#define ui(width, name) \
xui(width, name, current->name, 0, MAX_UINT_BITS(width), 0, )
#define uir(width, name) \
xui(width, name, current->name, 1, MAX_UINT_BITS(width), 0, )
#define uis(width, name, subs, ...) \
xui(width, name, current->name, 0, MAX_UINT_BITS(width), subs, __VA_ARGS__)
#define uirs(width, name, subs, ...) \
xui(width, name, current->name, 1, MAX_UINT_BITS(width), subs, __VA_ARGS__)
#define xui(width, name, var, range_min, range_max, subs, ...) \
xuia(width, #name, var, range_min, range_max, subs, __VA_ARGS__)
#define sis(width, name, subs, ...) \
xsi(width, name, current->name, subs, __VA_ARGS__)
#define marker_bit() \
bit("marker_bit", 1)
#define bit(string, value) do { \
av_unused uint32_t bit = value; \
xuia(1, string, bit, value, value, 0, ); \
} while (0)
#define READ
#define READWRITE read
#define RWContext GetBitContext
#define xuia(width, string, var, range_min, range_max, subs, ...) do { \
uint32_t value; \
CHECK(ff_cbs_read_unsigned(ctx, rw, width, string, \
SUBSCRIPTS(subs, __VA_ARGS__), \
&value, range_min, range_max)); \
var = value; \
} while (0)
#define xsi(width, name, var, subs, ...) do { \
int32_t value; \
CHECK(ff_cbs_read_signed(ctx, rw, width, #name, \
SUBSCRIPTS(subs, __VA_ARGS__), &value, \
MIN_INT_BITS(width), \
MAX_INT_BITS(width))); \
var = value; \
} while (0)
#define nextbits(width, compare, var) \
(get_bits_left(rw) >= width && \
(var = show_bits(rw, width)) == (compare))
#define infer(name, value) do { \
current->name = value; \
} while (0)
#include "cbs_mpeg2_syntax_template.c"
#undef READ
#undef READWRITE
#undef RWContext
#undef xuia
#undef xsi
#undef nextbits
#undef infer
#define WRITE
#define READWRITE write
#define RWContext PutBitContext
#define xuia(width, string, var, range_min, range_max, subs, ...) do { \
CHECK(ff_cbs_write_unsigned(ctx, rw, width, string, \
SUBSCRIPTS(subs, __VA_ARGS__), \
var, range_min, range_max)); \
} while (0)
#define xsi(width, name, var, subs, ...) do { \
CHECK(ff_cbs_write_signed(ctx, rw, width, #name, \
SUBSCRIPTS(subs, __VA_ARGS__), var, \
MIN_INT_BITS(width), \
MAX_INT_BITS(width))); \
} while (0)
#define nextbits(width, compare, var) (var)
#define infer(name, value) do { \
if (current->name != (value)) { \
av_log(ctx->log_ctx, AV_LOG_WARNING, "Warning: " \
"%s does not match inferred value: " \
"%"PRId64", but should be %"PRId64".\n", \
#name, (int64_t)current->name, (int64_t)(value)); \
} \
} while (0)
#include "cbs_mpeg2_syntax_template.c"
#undef WRITE
#undef READWRITE
#undef RWContext
#undef xuia
#undef xsi
#undef nextbits
#undef infer
static void cbs_mpeg2_free_picture_header(void *opaque, uint8_t *content)
{
MPEG2RawPictureHeader *picture = (MPEG2RawPictureHeader*)content;
av_buffer_unref(&picture->extra_information_picture.extra_information_ref);
av_freep(&content);
}
static void cbs_mpeg2_free_user_data(void *opaque, uint8_t *content)
{
MPEG2RawUserData *user = (MPEG2RawUserData*)content;
av_buffer_unref(&user->user_data_ref);
av_freep(&content);
}
static void cbs_mpeg2_free_slice(void *opaque, uint8_t *content)
{
MPEG2RawSlice *slice = (MPEG2RawSlice*)content;
av_buffer_unref(&slice->header.extra_information_slice.extra_information_ref);
av_buffer_unref(&slice->data_ref);
av_freep(&content);
}
static int cbs_mpeg2_split_fragment(CodedBitstreamContext *ctx,
CodedBitstreamFragment *frag,
int header)
{
const uint8_t *start, *end;
CodedBitstreamUnitType unit_type;
uint32_t start_code = -1;
size_t unit_size;
int err, i, final = 0;
start = avpriv_find_start_code(frag->data, frag->data + frag->data_size,
&start_code);
if (start_code >> 8 != 0x000001) {
// No start code found.
return AVERROR_INVALIDDATA;
}
for (i = 0;; i++) {
unit_type = start_code & 0xff;
if (start == frag->data + frag->data_size) {
// The last four bytes form a start code which constitutes
// a unit of its own. In this situation avpriv_find_start_code
// won't modify start_code at all so modify start_code so that
// the next unit will be treated as the last unit.
start_code = 0;
}
end = avpriv_find_start_code(start--, frag->data + frag->data_size,
&start_code);
// start points to the byte containing the start_code_identifier
// (may be the last byte of fragment->data); end points to the byte
// following the byte containing the start code identifier (or to
// the end of fragment->data).
if (start_code >> 8 == 0x000001) {
// Unit runs from start to the beginning of the start code
// pointed to by end (including any padding zeroes).
unit_size = (end - 4) - start;
} else {
// We didn't find a start code, so this is the final unit.
unit_size = end - start;
final = 1;
}
err = ff_cbs_insert_unit_data(ctx, frag, i, unit_type, (uint8_t*)start,
unit_size, frag->data_ref);
if (err < 0)
return err;
if (final)
break;
start = end;
}
return 0;
}
static int cbs_mpeg2_read_unit(CodedBitstreamContext *ctx,
CodedBitstreamUnit *unit)
{
GetBitContext gbc;
int err;
err = init_get_bits(&gbc, unit->data, 8 * unit->data_size);
if (err < 0)
return err;
if (MPEG2_START_IS_SLICE(unit->type)) {
MPEG2RawSlice *slice;
int pos, len;
err = ff_cbs_alloc_unit_content(ctx, unit, sizeof(*slice),
&cbs_mpeg2_free_slice);
if (err < 0)
return err;
slice = unit->content;
err = cbs_mpeg2_read_slice_header(ctx, &gbc, &slice->header);
if (err < 0)
return err;
if (!get_bits_left(&gbc))
return AVERROR_INVALIDDATA;
pos = get_bits_count(&gbc);
len = unit->data_size;
slice->data_size = len - pos / 8;
slice->data_ref = av_buffer_ref(unit->data_ref);
if (!slice->data_ref)
return AVERROR(ENOMEM);
slice->data = unit->data + pos / 8;
slice->data_bit_start = pos % 8;
} else {
switch (unit->type) {
#define START(start_code, type, read_func, free_func) \
case start_code: \
{ \
type *header; \
err = ff_cbs_alloc_unit_content(ctx, unit, \
sizeof(*header), free_func); \
if (err < 0) \
return err; \
header = unit->content; \
err = cbs_mpeg2_read_ ## read_func(ctx, &gbc, header); \
if (err < 0) \
return err; \
} \
break;
START(MPEG2_START_PICTURE, MPEG2RawPictureHeader,
picture_header, &cbs_mpeg2_free_picture_header);
START(MPEG2_START_USER_DATA, MPEG2RawUserData,
user_data, &cbs_mpeg2_free_user_data);
START(MPEG2_START_SEQUENCE_HEADER, MPEG2RawSequenceHeader,
sequence_header, NULL);
START(MPEG2_START_EXTENSION, MPEG2RawExtensionData,
extension_data, NULL);
START(MPEG2_START_GROUP, MPEG2RawGroupOfPicturesHeader,
group_of_pictures_header, NULL);
START(MPEG2_START_SEQUENCE_END, MPEG2RawSequenceEnd,
sequence_end, NULL);
#undef START
default:
return AVERROR(ENOSYS);
}
}
return 0;
}
static int cbs_mpeg2_write_header(CodedBitstreamContext *ctx,
CodedBitstreamUnit *unit,
PutBitContext *pbc)
{
int err;
switch (unit->type) {
#define START(start_code, type, func) \
case start_code: \
err = cbs_mpeg2_write_ ## func(ctx, pbc, unit->content); \
break;
START(MPEG2_START_PICTURE, MPEG2RawPictureHeader, picture_header);
START(MPEG2_START_USER_DATA, MPEG2RawUserData, user_data);
START(MPEG2_START_SEQUENCE_HEADER, MPEG2RawSequenceHeader, sequence_header);
START(MPEG2_START_EXTENSION, MPEG2RawExtensionData, extension_data);
START(MPEG2_START_GROUP, MPEG2RawGroupOfPicturesHeader,
group_of_pictures_header);
START(MPEG2_START_SEQUENCE_END, MPEG2RawSequenceEnd, sequence_end);
#undef START
default:
av_log(ctx->log_ctx, AV_LOG_ERROR, "Write unimplemented for start "
"code %02"PRIx32".\n", unit->type);
return AVERROR_PATCHWELCOME;
}
return err;
}
static int cbs_mpeg2_write_slice(CodedBitstreamContext *ctx,
CodedBitstreamUnit *unit,
PutBitContext *pbc)
{
MPEG2RawSlice *slice = unit->content;
int err;
err = cbs_mpeg2_write_slice_header(ctx, pbc, &slice->header);
if (err < 0)
return err;
if (slice->data) {
size_t rest = slice->data_size - (slice->data_bit_start + 7) / 8;
uint8_t *pos = slice->data + slice->data_bit_start / 8;
av_assert0(slice->data_bit_start >= 0 &&
slice->data_size > slice->data_bit_start / 8);
if (slice->data_size * 8 + 8 > put_bits_left(pbc))
return AVERROR(ENOSPC);
// First copy the remaining bits of the first byte
if (slice->data_bit_start % 8)
put_bits(pbc, 8 - slice->data_bit_start % 8,
*pos++ & MAX_UINT_BITS(8 - slice->data_bit_start % 8));
if (put_bits_count(pbc) % 8 == 0) {
// If the writer is aligned at this point,
// memcpy can be used to improve performance.
// This is the normal case.
flush_put_bits(pbc);
memcpy(put_bits_ptr(pbc), pos, rest);
skip_put_bytes(pbc, rest);
} else {
// If not, we have to copy manually:
for (; rest > 3; rest -= 4, pos += 4)
put_bits32(pbc, AV_RB32(pos));
for (; rest; rest--, pos++)
put_bits(pbc, 8, *pos);
// Align with zeros
put_bits(pbc, 8 - put_bits_count(pbc) % 8, 0);
}
}
return 0;
}
static int cbs_mpeg2_write_unit(CodedBitstreamContext *ctx,
CodedBitstreamUnit *unit,
PutBitContext *pbc)
{
if (MPEG2_START_IS_SLICE(unit->type))
return cbs_mpeg2_write_slice (ctx, unit, pbc);
else
return cbs_mpeg2_write_header(ctx, unit, pbc);
}
static int cbs_mpeg2_assemble_fragment(CodedBitstreamContext *ctx,
CodedBitstreamFragment *frag)
{
uint8_t *data;
size_t size, dp;
int i;
size = 0;
for (i = 0; i < frag->nb_units; i++)
size += 3 + frag->units[i].data_size;
frag->data_ref = av_buffer_alloc(size + AV_INPUT_BUFFER_PADDING_SIZE);
if (!frag->data_ref)
return AVERROR(ENOMEM);
data = frag->data_ref->data;
dp = 0;
for (i = 0; i < frag->nb_units; i++) {
CodedBitstreamUnit *unit = &frag->units[i];
data[dp++] = 0;
data[dp++] = 0;
data[dp++] = 1;
memcpy(data + dp, unit->data, unit->data_size);
dp += unit->data_size;
}
av_assert0(dp == size);
memset(data + size, 0, AV_INPUT_BUFFER_PADDING_SIZE);
frag->data = data;
frag->data_size = size;
return 0;
}
const CodedBitstreamType ff_cbs_type_mpeg2 = {
.codec_id = AV_CODEC_ID_MPEG2VIDEO,
.priv_data_size = sizeof(CodedBitstreamMPEG2Context),
.split_fragment = &cbs_mpeg2_split_fragment,
.read_unit = &cbs_mpeg2_read_unit,
.write_unit = &cbs_mpeg2_write_unit,
.assemble_fragment = &cbs_mpeg2_assemble_fragment,
};
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