lavc: Add coded bitstream read/write support for MPEG-2

(cherry picked from commit 2bc9ba8d3c41f3a8e56484bd67b05040c7909a01)
(cherry picked from commit a41b69b5eb950c10d8ede472bcc4e88ce4246db9)

1 files changed, 414 insertions, 0 deletions

diff --git a/libavcodec/cbs_mpeg2.c b/libavcodec/cbs_mpeg2.c
new file mode 100644
index 0000000000..d137762227
--- /dev/null
+++ b/libavcodec/cbs_mpeg2.c
@@ -0,0 +1,414 @@
+/*
+ * 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 READ
+#define READWRITE read
+#define RWContext GetBitContext
+
+#define xui(width, name, var) do { \
+        uint32_t value = 0; \
+        CHECK(ff_cbs_read_unsigned(ctx, rw, width, #name, \
+                                   &value, 0, (1 << width) - 1)); \
+        var = value; \
+    } while (0)
+
+#define ui(width, name) \
+        xui(width, name, current->name)
+
+#define marker_bit() do { \
+        av_unused int one = 1; \
+        CHECK(ff_cbs_read_unsigned(ctx, rw, 1, "marker_bit", &one, 1, 1)); \
+    } while (0)
+
+#define nextbits(width, compare, var) \
+    (get_bits_left(rw) >= width && \
+     (var = show_bits(rw, width)) == (compare))
+
+#include "cbs_mpeg2_syntax_template.c"
+
+#undef READ
+#undef READWRITE
+#undef RWContext
+#undef xui
+#undef ui
+#undef marker_bit
+#undef nextbits
+
+
+#define WRITE
+#define READWRITE write
+#define RWContext PutBitContext
+
+#define xui(width, name, var) do { \
+        CHECK(ff_cbs_write_unsigned(ctx, rw, width, #name, \
+                                    var, 0, (1 << width) - 1)); \
+    } while (0)
+
+#define ui(width, name) \
+        xui(width, name, current->name)
+
+#define marker_bit() do { \
+        CHECK(ff_cbs_write_unsigned(ctx, rw, 1, "marker_bit", 1, 1, 1)); \
+    } while (0)
+
+#define nextbits(width, compare, var) (var)
+
+#include "cbs_mpeg2_syntax_template.c"
+
+#undef READ
+#undef READWRITE
+#undef RWContext
+#undef xui
+#undef ui
+#undef marker_bit
+#undef nextbits
+
+
+static int cbs_mpeg2_split_fragment(CodedBitstreamContext *ctx,
+                                    CodedBitstreamFragment *frag,
+                                    int header)
+{
+    const uint8_t *start, *end;
+    uint8_t *unit_data;
+    uint32_t start_code = -1, next_start_code = -1;
+    size_t unit_size;
+    int err, i, unit_type;
+
+    start = avpriv_find_start_code(frag->data, frag->data + frag->data_size,
+                                   &start_code);
+    for (i = 0;; i++) {
+        end = avpriv_find_start_code(start, frag->data + frag->data_size,
+                                     &next_start_code);
+
+        unit_type = start_code & 0xff;
+
+        // The start and end pointers point at to the byte following the
+        // start_code_identifier in the start code that they found.
+        if (end == frag->data + frag->data_size) {
+            // We didn't find a start code, so this is the final unit.
+            unit_size = end - (start - 1);
+        } else {
+            // Unit runs from start to the beginning of the start code
+            // pointed to by end (including any padding zeroes).
+            unit_size = (end - 4) - (start - 1);
+        }
+
+        unit_data = av_malloc(unit_size + AV_INPUT_BUFFER_PADDING_SIZE);
+        if (!unit_data)
+            return AVERROR(ENOMEM);
+        memcpy(unit_data, start - 1, unit_size);
+        memset(unit_data + unit_size, 0, AV_INPUT_BUFFER_PADDING_SIZE);
+
+        err = ff_cbs_insert_unit_data(ctx, frag, i, unit_type,
+                                      unit_data, unit_size);
+        if (err < 0) {
+            av_freep(&unit_data);
+            return err;
+        }
+
+        if (end == frag->data + frag->data_size)
+            break;
+
+        start_code = next_start_code;
+        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;
+
+        slice = av_mallocz(sizeof(*slice));
+        if (!slice)
+            return AVERROR(ENOMEM);
+        err = cbs_mpeg2_read_slice_header(ctx, &gbc, &slice->header);
+        if (err < 0) {
+            av_free(slice);
+            return err;
+        }
+
+        pos = get_bits_count(&gbc);
+        len = unit->data_size;
+
+        slice->data_size = len - pos / 8;
+        slice->data = av_malloc(slice->data_size +
+                                AV_INPUT_BUFFER_PADDING_SIZE);
+        if (!slice->data) {
+            av_free(slice);
+            return AVERROR(ENOMEM);
+        }
+
+        memcpy(slice->data,
+               unit->data + pos / 8, slice->data_size);
+        memset(slice->data + slice->data_size, 0,
+               AV_INPUT_BUFFER_PADDING_SIZE);
+        slice->data_bit_start = pos % 8;
+
+        unit->content = slice;
+
+    } else {
+        switch (unit->type) {
+#define START(start_code, type, func) \
+        case start_code: \
+            { \
+                type *header; \
+                header = av_mallocz(sizeof(*header)); \
+                if (!header) \
+                    return AVERROR(ENOMEM); \
+                err = cbs_mpeg2_read_ ## func(ctx, &gbc, header); \
+                if (err < 0) { \
+                    av_free(header); \
+                    return err; \
+                } \
+                unit->content = header; \
+            } \
+            break;
+            START(0x00, MPEG2RawPictureHeader,  picture_header);
+            START(0xb2, MPEG2RawUserData,       user_data);
+            START(0xb3, MPEG2RawSequenceHeader, sequence_header);
+            START(0xb5, MPEG2RawExtensionData,  extension_data);
+            START(0xb8, MPEG2RawGroupOfPicturesHeader, group_of_pictures_header);
+#undef START
+        default:
+            av_log(ctx->log_ctx, AV_LOG_ERROR, "Unknown start code %02x.\n",
+                   unit->type);
+            return AVERROR_INVALIDDATA;
+        }
+    }
+
+    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(0x00, MPEG2RawPictureHeader,  picture_header);
+        START(0xb2, MPEG2RawUserData,       user_data);
+        START(0xb3, MPEG2RawSequenceHeader, sequence_header);
+        START(0xb5, MPEG2RawExtensionData,  extension_data);
+        START(0xb8, MPEG2RawGroupOfPicturesHeader, group_of_pictures_header);
+#undef START
+    default:
+        av_log(ctx->log_ctx, AV_LOG_ERROR, "Write unimplemented for start "
+               "code %02"PRIu32".\n", unit->type);
+        return AVERROR_PATCHWELCOME;
+    }
+
+    return err;
+}
+
+static int cbs_mpeg2_write_slice(CodedBitstreamContext *ctx,
+                                 CodedBitstreamUnit *unit,
+                                 PutBitContext *pbc)
+{
+    MPEG2RawSlice *slice = unit->content;
+    GetBitContext gbc;
+    size_t bits_left;
+    int err;
+
+    err = cbs_mpeg2_write_slice_header(ctx, pbc, &slice->header);
+    if (err < 0)
+        return err;
+
+    if (slice->data) {
+        if (slice->data_size * 8 + 8 > put_bits_left(pbc))
+            return AVERROR(ENOSPC);
+
+        init_get_bits(&gbc, slice->data, slice->data_size * 8);
+        skip_bits_long(&gbc, slice->data_bit_start);
+
+        while (get_bits_left(&gbc) > 15)
+            put_bits(pbc, 16, get_bits(&gbc, 16));
+
+        bits_left = get_bits_left(&gbc);
+        put_bits(pbc, bits_left, get_bits(&gbc, bits_left));
+
+        // Align with zeroes.
+        while (put_bits_count(pbc) % 8 != 0)
+            put_bits(pbc, 1, 0);
+    }
+
+    return 0;
+}
+
+static int cbs_mpeg2_write_unit(CodedBitstreamContext *ctx,
+                                CodedBitstreamUnit *unit)
+{
+    CodedBitstreamMPEG2Context *priv = ctx->priv_data;
+    PutBitContext pbc;
+    int err;
+
+    if (!priv->write_buffer) {
+        // Initial write buffer size is 1MB.
+        priv->write_buffer_size = 1024 * 1024;
+
+    reallocate_and_try_again:
+        err = av_reallocp(&priv->write_buffer, priv->write_buffer_size);
+        if (err < 0) {
+            av_log(ctx->log_ctx, AV_LOG_ERROR, "Unable to allocate a "
+                   "sufficiently large write buffer (last attempt "
+                   "%zu bytes).\n", priv->write_buffer_size);
+            return err;
+        }
+    }
+
+    init_put_bits(&pbc, priv->write_buffer, priv->write_buffer_size);
+
+    if (unit->type >= 0x01 && unit->type <= 0xaf)
+        err = cbs_mpeg2_write_slice(ctx, unit, &pbc);
+    else
+        err = cbs_mpeg2_write_header(ctx, unit, &pbc);
+
+    if (err == AVERROR(ENOSPC)) {
+        // Overflow.
+        priv->write_buffer_size *= 2;
+        goto reallocate_and_try_again;
+    }
+    if (err < 0) {
+        // Write failed for some other reason.
+        return err;
+    }
+
+    if (put_bits_count(&pbc) % 8)
+        unit->data_bit_padding = 8 - put_bits_count(&pbc) % 8;
+    else
+        unit->data_bit_padding = 0;
+
+    unit->data_size = (put_bits_count(&pbc) + 7) / 8;
+    flush_put_bits(&pbc);
+
+    err = av_reallocp(&unit->data, unit->data_size);
+    if (err < 0)
+        return err;
+
+    memcpy(unit->data, priv->write_buffer, unit->data_size);
+
+    return 0;
+}
+
+static int cbs_mpeg2_assemble_fragment(CodedBitstreamContext *ctx,
+                                       CodedBitstreamFragment *frag)
+{
+    uint8_t *data;
+    size_t size, dp, sp;
+    int i;
+
+    size = 0;
+    for (i = 0; i < frag->nb_units; i++)
+        size += 3 + frag->units[i].data_size;
+
+    data = av_malloc(size);
+    if (!data)
+        return AVERROR(ENOMEM);
+
+    dp = 0;
+    for (i = 0; i < frag->nb_units; i++) {
+        CodedBitstreamUnit *unit = &frag->units[i];
+
+        data[dp++] = 0;
+        data[dp++] = 0;
+        data[dp++] = 1;
+
+        for (sp = 0; sp < unit->data_size; sp++)
+            data[dp++] = unit->data[sp];
+    }
+
+    av_assert0(dp == size);
+
+    frag->data      = data;
+    frag->data_size = size;
+
+    return 0;
+}
+
+static void cbs_mpeg2_free_unit(CodedBitstreamUnit *unit)
+{
+    if (MPEG2_START_IS_SLICE(unit->type)) {
+        MPEG2RawSlice *slice = unit->content;
+        av_freep(&slice->data);
+        av_freep(&slice->header.extra_information);
+    } else if (unit->type == MPEG2_START_USER_DATA) {
+        MPEG2RawUserData *user = unit->content;
+        av_freep(&user->user_data);
+    }
+    av_freep(&unit->content);
+}
+
+static void cbs_mpeg2_close(CodedBitstreamContext *ctx)
+{
+    CodedBitstreamMPEG2Context *priv = ctx->priv_data;
+
+    av_freep(&priv->write_buffer);
+}
+
+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,
+
+    .free_unit         = &cbs_mpeg2_free_unit,
+    .close             = &cbs_mpeg2_close,
+};