mirror of https://git.ffmpeg.org/ffmpeg.git
avcodec/jpeglsenc: Avoid intermediate buffer, allow user-supplied buffers
Up until now, the JPEG-LS encoder allocated a worst-case-sized packet at the beginning of each encode2 call; then it wrote the packet header into its destination buffer and encoded the actual packet data; said data is written into another worst-case-sized buffer, because it needs to be escaped before being written into the packet buffer. Finally, because the packet buffer is worst-case-sized, the generic code copies the actually used part into a fresh buffer. This commit changes this: Allocating the packet and writing the header into it is deferred until the actual data has been encoded and its size is known. This gives a good upper bound for the needed size of the packet buffer (the upper bound might be 1/15 too large) and so one can avoid the implicit intermediate buffer and support user-supplied buffers by using ff_get_encode_buffer(). Signed-off-by: Andreas Rheinhardt <andreas.rheinhardt@outlook.com>
This commit is contained in:
Andreas Rheinhardt
parent
634a187b9b
commit
f249c32eff
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@ -27,6 +27,7 @@
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#include "avcodec.h"
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#include "bytestream.h"
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#include "encode.h"
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#include "get_bits.h"
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#include "put_bits.h"
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#include "golomb.h"
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@ -283,53 +284,23 @@ static int encode_picture_ls(AVCodecContext *avctx, AVPacket *pkt,
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const uint8_t *in;
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uint8_t *last = NULL;
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JLSState state = { 0 };
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int i, size, ret;
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size_t size;
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int i, ret, size_in_bits;
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int comps;
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if ((ret = ff_alloc_packet2(avctx, pkt, ctx->size, 0)) < 0)
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return ret;
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last = av_mallocz(FFABS(p->linesize[0]));
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if (!last)
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return AVERROR(ENOMEM);
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bytestream2_init_writer(&pb, pkt->data, pkt->size);
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init_put_bits(&pb2, ctx->buf, ctx->size);
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/* write our own JPEG header, can't use mjpeg_picture_header */
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comps = ctx->comps;
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put_marker_byteu(&pb, SOI);
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put_marker_byteu(&pb, SOF48);
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bytestream2_put_be16u(&pb, 8 + comps * 3); // header size depends on components
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bytestream2_put_byteu(&pb, (avctx->pix_fmt == AV_PIX_FMT_GRAY16) ? 16 : 8); // bpp
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bytestream2_put_be16u(&pb, avctx->height);
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bytestream2_put_be16u(&pb, avctx->width);
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bytestream2_put_byteu(&pb, comps); // components
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for (i = 1; i <= comps; i++) {
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bytestream2_put_byteu(&pb, i); // component ID
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bytestream2_put_byteu(&pb, 0x11); // subsampling: none
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bytestream2_put_byteu(&pb, 0); // Tiq, used by JPEG-LS ext
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}
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put_marker_byteu(&pb, SOS);
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bytestream2_put_be16u(&pb, 6 + comps * 2);
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bytestream2_put_byteu(&pb, comps);
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for (i = 1; i <= comps; i++) {
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bytestream2_put_byteu(&pb, i); // component ID
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bytestream2_put_byteu(&pb, 0); // mapping index: none
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}
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bytestream2_put_byteu(&pb, ctx->pred);
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bytestream2_put_byteu(&pb, (comps > 1) ? 1 : 0); // interleaving: 0 - plane, 1 - line
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bytestream2_put_byteu(&pb, 0); // point transform: none
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/* initialize JPEG-LS state from JPEG parameters */
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state.near = ctx->pred;
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state.bpp = (avctx->pix_fmt == AV_PIX_FMT_GRAY16) ? 16 : 8;
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ff_jpegls_reset_coding_parameters(&state, 0);
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ff_jpegls_init_state(&state);
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ls_store_lse(&state, &pb);
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in = p->data[0];
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if (avctx->pix_fmt == AV_PIX_FMT_GRAY8) {
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int t = 0;
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@ -378,17 +349,63 @@ static int encode_picture_ls(AVCodecContext *avctx, AVPacket *pkt,
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in += p->linesize[0];
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}
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}
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/* the specification says that after doing 0xff escaping unused bits in
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* the last byte must be set to 0, so just append 7 "optional" zero bits
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* to avoid special-casing. */
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av_free(last);
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/* Now the actual image data has been written, which enables us to estimate
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* the needed packet size: For every 15 input bits, an escape bit might be
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* added below; and if put_bits_count % 15 is >= 8, then another bit might
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* be added.
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* Furthermore the specification says that after doing 0xff escaping unused
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* bits in the last byte must be set to 0, so just append 7 "optional" zero
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* bits to avoid special-casing. This also simplifies the size calculation:
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* Properly rounding up is now automatically baked-in. */
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put_bits(&pb2, 7, 0);
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size = put_bits_count(&pb2);
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/* Make sure that the bit count + padding is representable in an int;
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necessary for put_bits_count() as well as for using a GetBitContext. */
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if (put_bytes_count(&pb2, 0) > INT_MAX / 8 - AV_INPUT_BUFFER_PADDING_SIZE)
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return AVERROR(ERANGE);
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size_in_bits = put_bits_count(&pb2);
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flush_put_bits(&pb2);
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size = size_in_bits * 2U / 15;
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size += 2 + 2 + 2 + 1 + 2 + 2 + 1 + comps * (1 + 1 + 1) + 2 + 2 + 1
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+ comps * (1 + 1) + 1 + 1 + 1; /* Header */
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size += 2 + 2 + 1 + 2 + 2 + 2 + 2 + 2; /* LSE */
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size += 2; /* EOI */
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if ((ret = ff_get_encode_buffer(avctx, pkt, size, 0)) < 0)
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return ret;
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bytestream2_init_writer(&pb, pkt->data, pkt->size);
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/* write our own JPEG header, can't use mjpeg_picture_header */
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put_marker_byteu(&pb, SOI);
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put_marker_byteu(&pb, SOF48);
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bytestream2_put_be16u(&pb, 8 + comps * 3); // header size depends on components
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bytestream2_put_byteu(&pb, (avctx->pix_fmt == AV_PIX_FMT_GRAY16) ? 16 : 8); // bpp
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bytestream2_put_be16u(&pb, avctx->height);
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bytestream2_put_be16u(&pb, avctx->width);
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bytestream2_put_byteu(&pb, comps); // components
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for (i = 1; i <= comps; i++) {
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bytestream2_put_byteu(&pb, i); // component ID
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bytestream2_put_byteu(&pb, 0x11); // subsampling: none
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bytestream2_put_byteu(&pb, 0); // Tiq, used by JPEG-LS ext
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}
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put_marker_byteu(&pb, SOS);
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bytestream2_put_be16u(&pb, 6 + comps * 2);
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bytestream2_put_byteu(&pb, comps);
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for (i = 1; i <= comps; i++) {
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bytestream2_put_byteu(&pb, i); // component ID
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bytestream2_put_byteu(&pb, 0); // mapping index: none
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}
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bytestream2_put_byteu(&pb, ctx->pred);
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bytestream2_put_byteu(&pb, (comps > 1) ? 1 : 0); // interleaving: 0 - plane, 1 - line
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bytestream2_put_byteu(&pb, 0); // point transform: none
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ls_store_lse(&state, &pb);
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/* do escape coding */
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init_get_bits(&gb, pb2.buf, size);
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size -= 7;
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while (get_bits_count(&gb) < size) {
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init_get_bits(&gb, pb2.buf, size_in_bits);
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size_in_bits -= 7;
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while (get_bits_count(&gb) < size_in_bits) {
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int v;
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v = get_bits(&gb, 8);
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bytestream2_put_byte(&pb, v);
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@ -397,15 +414,14 @@ static int encode_picture_ls(AVCodecContext *avctx, AVPacket *pkt,
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bytestream2_put_byte(&pb, v);
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}
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}
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av_freep(&last);
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/* End of image */
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put_marker_byte(&pb, EOI);
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emms_c();
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pkt->size = bytestream2_tell_p(&pb);
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pkt->flags |= AV_PKT_FLAG_KEY;
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av_shrink_packet(pkt, bytestream2_tell_p(&pb));
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*got_packet = 1;
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return 0;
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}
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@ -468,9 +484,9 @@ const AVCodec ff_jpegls_encoder = {
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.long_name = NULL_IF_CONFIG_SMALL("JPEG-LS"),
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.type = AVMEDIA_TYPE_VIDEO,
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.id = AV_CODEC_ID_JPEGLS,
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.capabilities = AV_CODEC_CAP_DR1 | AV_CODEC_CAP_FRAME_THREADS,
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.priv_data_size = sizeof(JPEGLSContext),
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.priv_class = &jpegls_class,
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.capabilities = AV_CODEC_CAP_FRAME_THREADS,
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.init = encode_jpegls_init,
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.encode2 = encode_picture_ls,
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.close = encode_jpegls_close,
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